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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2019	Apr. 22, 2020	Jun. 30, 2019
Document And Entity Information [Abstract]
Entity Registrant Name	POWER SOLUTIONS INTERNATIONAL, INC.
Entity Central Index Key	0001137091
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		22,857,602
Entity Interactive Data Current	Yes
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	No
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Public Float			$ 49.0

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 3	$ 54
Accounts receivable, net of allowances of $3,561 and $2,596 as of December 31, 2019 and December 31, 2018, respectively	104,515	86,471
Income tax receivable	1,055	973
Inventories, net	108,839	105,614
Prepaid expenses and other current assets	8,110	22,917
Total current assets	222,522	216,029
Property, plant and equipment, net	23,194	24,266
Intangible assets, net	13,372	17,010
Goodwill	29,835	29,835
Other noncurrent assets	24,749	2,742
TOTAL ASSETS	313,672	289,882
Current liabilities:
Accounts payable	75,835	85,218
Current maturities of long-term debt	195	80
Revolving line of credit	39,527	54,613
Warrant liability	0	35,100
Other accrued liabilities	66,030	45,700
Total current liabilities	181,587	220,711
Deferred income taxes	1,105	647
Long-term debt, net of current maturities	55,657	55,088
Noncurrent contract liabilities	17,998	14,611
Other noncurrent liabilities	28,828	17,403
TOTAL LIABILITIES	285,175	308,460
STOCKHOLDERS’ EQUITY (DEFICIT)
Preferred stock – $0.001 par value. Shares authorized: 5,000. No shares issued and outstanding at all dates.	0	0
Common stock – $0.001 par value; 50,000 shares authorized; 23,117 and 19,067 shares issued; 22,857 and 18,638 shares outstanding at December 31, 2019 and December 31, 2018, respectively	23	19
Additional paid-in capital	165,527	126,412
Accumulated deficit	(126,912)	(135,160)
Treasury stock, at cost, 260 and 429 shares at December 31, 2019 and December 31, 2018, respectively	(10,141)	(9,849)
TOTAL STOCKHOLDERS’ EQUITY (DEFICIT)	28,497	(18,578)
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY (DEFICIT)	$ 313,672	$ 289,882

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Accounts receivable allowance	$ 3,561	$ 2,596
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, authorized (in shares)	5,000,000	5,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	50,000,000	50,000,000
Common stock, issued (in shares)	23,117,000	19,067,000
Common stock, outstanding (in shares)	22,857,000	18,638,000
Treasury stock (in shares)	260,000	429,000

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Net sales	$ 546,076	$ 496,038
Cost of sales	446,188	437,269
Gross profit	99,888	58,769
Operating expenses:
Research, development and engineering expenses	24,932	28,601
Selling, general and administrative expenses	54,114	59,631
Asset impairment charges	1	2,234
Amortization of intangible assets	3,638	5,008
Total operating expenses	82,685	95,474
Operating income (loss)	17,203	(36,705)
Other expense:
Interest expense	7,871	7,628
Loss from change in value and exercise of warrants	1,352	10,400
Other income, net	(677)	(176)
Total other expense	8,546	17,852
Income (loss) before income taxes	8,657	(54,557)
Income tax expense	409	169
Net income (loss)	$ 8,248	$ (54,726)
Weighted-average common shares outstanding:
Basic (in shares)	21,512	18,585
Diluted (in shares)	21,530	18,585
Earnings (loss) per common share:
Basic (in dollars per share)	$ 0.38	$ (2.94)
Diluted (in dollars per share)	$ 0.38	$ (2.94)

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Treasury Stock
Beginning balance at Dec. 31, 2017	$ 32,172	$ 19	$ 123,838	$ (82,147)	$ (9,538)
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(54,726)			(54,726)
Stock-based compensation expense	2,663		2,974		(311)
Payment of withholding taxes for net settlement of stock-based awards	(400)		(400)
Ending balance at Dec. 31, 2018	(18,578)	19	126,412	(135,160)	(9,849)
Increase (Decrease) in Stockholders' Equity
Net income (loss)	8,248			8,248
Stock-based compensation expense	1,248		1,540		(292)
Payment of withholding taxes for net settlement of stock-based awards	(489)		(489)
Issuance of common stock to Weichai	38,068	4	38,064
Ending balance at Dec. 31, 2019	$ 28,497	$ 23	$ 165,527	$ (126,912)	$ (10,141)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Cash provided by (used in) operating activities
Net income (loss)	$ 8,248	$ (54,726)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Amortization of intangible assets	3,638	5,008
Depreciation	5,161	5,196
Change in value and exercise of warrants	1,352	10,400
Stock-based compensation expense	1,248	2,663
Amortization of financing fees	698	1,497
Deferred income taxes	457	(56)
Asset impairment charges	1	2,234
Other non-cash adjustments, net	276	2,085
Changes in operating assets and liabilities:
Accounts receivable, net	(18,095)	(17,890)
Inventory, net	(3,977)	(26,202)
Prepaid expenses and other assets	17,125	(761)
Accounts payable	(9,494)	33,968
Accrued expenses	13,948	11,630
Other noncurrent liabilities	(2,429)	18,786
Net cash provided by (used in) operating activities	18,157	(6,168)
Cash used in investing activities
Capital expenditures	(3,681)	(3,645)
Asset acquisitions	0	(6,595)
Other investing activities, net	23	1
Net cash used in investing activities	(3,658)	(10,239)
Cash (used in) provided by financing activities
Proceeds from revolving line of credit	544,146	516,440
Repayments of revolving line of credit	(559,232)	(498,881)
Proceeds from Weichai Warrant exercise	1,616	0
Other financing activities, net	(1,080)	(1,098)
Net cash (used in) provided by financing activities	(14,550)	16,461
Net (decrease) increase in cash and restricted cash	(51)	54
Cash and restricted cash at beginning of the year	54	0
Cash and restricted cash at end of the year	$ 3	$ 54

Summary of Significant Accounting Policies and Other Information

12 Months Ended

Dec. 31, 2019

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Summary of Significant Accounting Policies and Other Information

Nature of Business Operations

Power Solutions International, Inc. (“Power Solutions,” “PSI” or the “Company”), a Delaware corporation, is a global producer and distributor of a broad range of high-performance, certified, low-emission power systems, including alternative-fueled power systems for original equipment manufacturers (“OEMs”) of off-highway industrial equipment and certain on-road vehicles and large custom-engineered integrated electrical power generation systems.

The Company’s customers include large, industry-leading and multinational organizations. The Company’s products and services are sold predominantly to customers throughout North America as well as to customers located throughout the Pacific Rim and Europe. The Company’s power systems are highly engineered, comprehensive systems which, through the Company’s technologically sophisticated development and manufacturing processes, including its in-house design, prototyping, testing and engineering capabilities and its analysis and determination of the specific components to be integrated into a given power system (driven in large part by emission standards and cost considerations), allow the Company to provide its customers with power systems customized to meet specific OEM application requirements, other technical customers’ specifications and requirements imposed by environmental regulatory bodies.

The Company’s power system configurations range from a basic engine integrated with appropriate fuel system components to completely packaged power systems that include any combination of cooling systems, electronic systems, air intake systems, fuel systems, housings, power takeoff systems, exhaust systems, hydraulic systems, enclosures, brackets, hoses, tubes and other assembled componentry. The Company also designs and manufactures large, custom-engineered integrated electrical power generation systems for both standby and prime power applications. The Company purchases engines from third-party suppliers and produces internally designed engines, all of which are then integrated into its power systems.

Of the other components that the Company integrates into its power systems, a substantial portion consist of internally designed components and components for which it coordinates significant design efforts with third-party suppliers, with the remainder consisting largely of parts that are sourced off-the-shelf from third-party suppliers. Some of the key components (including purchased engines) embody proprietary intellectual property of the Company’s suppliers. As a result of its design and manufacturing capabilities, the Company is able to provide its customers with a power system that can be incorporated into a customer’s specified application. In addition to the certified products described above, the Company sells diesel, gasoline and non-certified power systems and aftermarket components.

Stock Ownership and Control

In March 2017, the Company executed a share purchase agreement (the “SPA”) with Weichai America Corp., a wholly owned subsidiary of Weichai Power Co., Ltd. (HK2338, SZ000338) (herein collectively referred to as “Weichai”). Under the terms of the SPA, Weichai invested $60.0 million in the Company purchasing a combination of newly issued Common and Preferred Stock as well as a stock purchase warrant (the “Weichai Warrant”).

With the exercise of the Weichai Warrant in April 2019, Weichai owns a majority of the outstanding shares of the Company’s Common Stock. As a result, Weichai is able to exercise control over matters requiring stockholders’ approval, including the election of the directors, amendment of the Company’s Charter and approval of significant corporate transactions. This control could have the effect of delaying or preventing a change of control of the Company or changes in management and will make the approval of certain transactions impractical without the support of Weichai.

Weichai also entered into an Investor Rights Agreement (the “Rights Agreement”) with the Company upon execution of the SPA. The Rights Agreement provides Weichai with representation on the Company’s Board of Directors (the “Board”) and management representation rights. Weichai currently has three representatives on the Board. According to the Rights Agreement, once Weichai exercised the Weichai Warrant and became the majority owner of the Company’s outstanding shares of Common Stock calculated on a fully diluted as-converted basis (excluding certain excepted issuances), the Company became required to appoint to the Board an additional individual designated by Weichai or such additional numbers of individuals so that Weichai designees constitute the majority of the directors serving on the Board. As of the date of this filing, Weichai has not designated an additional representative to the Board. According to the Rights Agreement, during any period when the Company is a “controlled company” within the meaning of the NASDAQ Stock Market (“NASDAQ”) Listing Rules, it will take such measures as to avail itself of the “controlled company” exemptions available under Rule 5615 of the NASDAQ Listing Rules of Rules 5605(b), (d) and (e).

Going Concern Considerations

On April 2, 2020, the Company closed on its new senior secured revolving credit facility pursuant to that credit agreement dated March 27, 2020 between the Company and Standard Chartered Bank ("Standard Chartered"), as administrative agent (the "Credit Agreement"). The Credit Agreement, which allows the Company to borrow up to $130.0 million, matures on March 26, 2021 with an optional 60-day extension subject to certain conditions and payment of a 0.25% extension fee. See Note 6. Debt for further discussion of the Credit Agreement.

Significant uncertainties exist about the Company’s ability to refinance, extend, or repay its outstanding indebtedness, maintain sufficient liquidity to fund its business activities, and maintain compliance with the covenants and other requirements under the Credit Agreement. Based on the Company’s current forecasts, without additional financing, the Company anticipates that it will not have sufficient cash and cash equivalents to repay the Credit Agreement by March 26, 2021. Management plans to seek additional liquidity from its current or other lenders before March 26, 2021. There can be no assurance that the Company’s management will be able to successfully complete a financing on acceptable terms or repay this outstanding indebtedness, when required or if at all. The consolidated financial statements included in this Form 10-K do not include any adjustments that might result from the outcome of the Company’s efforts to address these issues.

Furthermore, if the Company cannot raise capital on acceptable terms, it may not, among other things, be able to do the following:


•	continue to expand the Company’s research and product investments and sales and marketing organization;


•	expand operations both organically and through acquisitions; and


•	respond to competitive pressures or unanticipated working capital requirements.

Additionally, as discussed in Note 16. Subsequent Events, in January 2020, the World Health Organization (“WHO”) announced a global health emergency because of a new strain of coronavirus (the “COVID-19 outbreak”) and the risks to the international community as the virus spreads globally. In March 2020, the WHO classified the COVID-19 outbreak as a global pandemic (the “COVID-19 pandemic”), based on the rapid increase in exposure globally. The potential impact of future disruptions, continued economic uncertainty, and continued depressed crude oil prices and declining rig count levels may have a material adverse impact on the results of operations, financial position, and liquidity of the Company.

The Company’s management has concluded that, due to uncertainties surrounding the Company’s future ability to refinance, extend, or repay its outstanding indebtedness, maintain sufficient liquidity to fund its business activities, and maintain compliance with the covenants and other requirements under the Credit Agreement, substantial doubt exists as to its ability to continue as a going concern within one year after the date that these financial statements are issued. The Company’s plans to alleviate the substantial doubt about its ability to continue as a going concern may not be successful, and it may be forced to limit its business activities or be unable to continue as a going concern, which would have a material adverse effect on its results of operations and financial condition.

The consolidated financial statements included herein have been prepared assuming that the Company will continue as a going concern and contemplating the realization of assets and the satisfaction of liabilities and commitments in the normal course of business. The Company’s ability to continue as a going concern is dependent on generating profitable operating results, having sufficient liquidity, maintaining compliance with the covenants and other requirements under the Credit Agreement and refinancing or repaying the indebtedness outstanding under this agreement.

Basis of Presentation and Consolidation

The consolidated financial statements include the accounts of Power Solutions International, Inc. and its wholly owned subsidiaries. The Company’s consolidated financial statements were prepared in accordance with generally accepted accounting principles in the United States (“U.S. GAAP”) and include the assets, liabilities, sales and expenses of all wholly owned subsidiaries and majority-owned subsidiaries in which the Company exercises control. All intercompany balances and transactions have been eliminated in consolidation.

The Company operates as one business and geographic operating segment. Operating segments are defined as components of a business that can earn revenues and incur expenses for which discrete financial information is available that is evaluated on a regular basis by the chief operating decision maker (“CODM”). The Company’s CODM is its principal executive officer, who decides how to allocate resources and assess performance. A single management team reports to the CODM, who manages the entire business. The Company’s CODM reviews consolidated statements of operations to make decisions, allocate resources and assess performance, and the CODM does not evaluate the profit or loss from any separate geography or product line.

Reclassifications

Certain amounts recorded in the prior-period consolidated financial statements presented have been reclassified to conform to the current-period financial statement presentation. These reclassifications had no effect on previously reported results of operations.

Concentrations

The following table presents customers individually accounting for more than 10% of the Company’s net sales:

The following table presents customers individually accounting for more than 10% of the Company’s accounts receivable:


**	Less than 10% of the total

The following table presents suppliers individually accounting for more than 10% of the Company’s purchases:

Use of Estimates

The preparation of consolidated financial statements in conformity with U.S. GAAP requires that management make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Significant estimates and assumptions include the valuation of allowances for uncollectible receivables, inventory reserves, warranty reserves, stock-based compensation, evaluation of goodwill, other intangibles, plant and equipment for impairment, and determination of useful lives of long-lived assets. Actual results could materially differ from those estimates.

Cash and Cash Equivalents

Cash equivalents consist of short-term, highly liquid investments that mature within three months or less. Such investments are stated at cost, which approximates fair value. The Company’s revolving credit agreement with Wells Fargo Bank, N.A. (“Wells Fargo”) included a “lockbox” arrangement that received all receipts and from which the Company could request increases in the revolver borrowings. On April 2, 2020, the Company entered into the Credit Agreement with Standard Chartered. The Credit Agreement does not include a “lockbox” arrangement. See Note 6. Debt for additional information regarding the Wells Fargo Credit Agreement (the “Wells Fargo Credit Agreement”) and the Credit Agreement.

Research and Development

Research and development (“R&D”) expenses are expensed when incurred. R&D expenses consist primarily of wages, materials, testing and consulting related to the development of new engines, parts and applications. These costs were $23.3 million and $26.8 million for 2019 and 2018, respectively.

Income Taxes

The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to be settled or realized. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date.

The Company records net deferred tax assets to the extent that it believes these assets will more likely than not be realized. In making such a determination, the Company considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies and results of recent operations.

The Company records uncertain tax positions in accordance with accounting guidance, on the basis of a two-step process whereby (i) it determines whether it is more likely than not that the tax positions will be sustained based on the technical merits of the position and (ii) for those tax positions that meet the more-likely-than-not recognition threshold, the Company recognizes the largest amount of tax benefit that is greater than 50% likely to be realized upon ultimate settlement with the related tax authority. Tax benefits related to uncertain tax positions taken or expected to be taken on a tax return are recorded when such benefits meet a more-likely-than-not threshold. Otherwise, these tax benefits are recorded when a tax position has been effectively settled, which means that the appropriate taxing authority has completed its examination even though the statute of limitations remains open, or the statute of limitation has expired. Interest and penalties related to uncertain tax positions are recognized as part of income tax expense and are accrued beginning in the period that such interest and penalties would be applicable under relevant tax law until such time that the related tax benefits are recognized.

Accounts Receivable and Allowance for Doubtful Accounts

Trade accounts receivable represent amounts billed to customers and not yet collected. Trade accounts receivable are recorded at the invoiced amount, which approximates net recoverable value, and generally do not bear interest. The allowance for doubtful accounts is the Company’s best estimate of the amount of probable credit losses in the existing accounts receivable and is established through a charge to selling, general and administrative expenses. The allowance is primarily determined based on historical collection experience and reviews of customer creditworthiness. Trade accounts receivable and the allowance for doubtful accounts are reviewed on a regular basis. When necessary, an allowance for the full amount of specific accounts deemed uncollectible is recorded. Accounts receivable losses are deducted from the allowance and the account balance is written off when the customer receivable is deemed uncollectible. Recoveries of previously written off balances are recognized when received. An allowance associated with anticipated future sales returns is also included in the allowance for doubtful accounts.

Insurance Recoveries

The Company records insurance recoveries related to amounts recorded as estimated losses on events covered by the Company’s insurance policies when management determines that the recovery is probable and the amount can be reasonably determined. As of December 31, 2019 and 2018, the Company had recorded assets related to insurance recoveries of $3.6 million and $16.0 million, respectively, primarily related to litigation reserves and related legal fees.

Inventories

The Company’s inventories consist primarily of engines and parts. Engines are valued at the lower of cost plus estimated freight-in or net realizable value. Parts are valued at the lower of cost or net realizable value. Net realizable value approximates replacement cost. Cost is principally determined using the first-in, first-out method and includes material, labor and manufacturing overhead. It is the Company’s policy to review inventories on a continuing basis for obsolete, excess and slow-moving items and to record valuation adjustments for such items in order to eliminate non-recoverable costs from inventory. Valuation adjustments are recorded in an inventory reserve account and reduce the cost basis of the inventory in the period in which the reduced valuation is determined. Inventory reserves are established based on quantities on hand, usage and sales history, customer orders, projected demand and utilization within a current or future power system. Specific analysis of individual items or groups of items is performed based on these same criteria, as well as on changes in market conditions or any other identified conditions.

Inventories consist of the following:



(in thousands)	As of December 31,
Inventories	2019			2018
Raw materials	$	90,677		$	90,877
Work in process	2,007			2,390
Finished goods	19,119			18,077
Total inventories	111,803			111,344
Inventory allowance	(2,964		)	(5,730		)
Inventories, net	$	108,839		$	105,614

Activity in the Company’s inventory allowance was as follows:



(in thousands)	For the Year Ended December 31,
Inventory Allowance	2019			2018
Balance at beginning of period	$	5,730		$	6,227
Charged to expense	677			2,153
Write-offs	(3,443		)	(2,650		)
Balance at end of period	$	2,964		$	5,730

Property, Plant and Equipment

Property, plant and equipment is carried at cost and presented net of accumulated depreciation and impairments. Depreciation is computed using the straight-line method over the estimated useful lives of the assets. Property, plant and equipment is evaluated periodically to determine if an adjustment to depreciable lives is warranted. Such evaluation is based principally on the expected utilization of the long-lived assets.

Repairs and maintenance costs are charged directly to expense as incurred. Major renewals or replacements that substantially extend the useful life of an asset are capitalized and depreciated.

Estimated useful lives by each type of asset category are as follows:



		Years
Buildings		Up to 39
Leasehold improvements		Lesser of (i) expected useful life of improvement or (ii) life of lease (including likely extension thereof)
Machinery and equipment		1 to 10

Intangible Assets

The Company’s intangible assets include customer relationships, developed technology, trade names and trademarks. Intangible assets are amortized on an accelerated basis over a period of time that approximates the pattern over which the Company expects to gain the estimated economic benefits, and such period generally ranges between three years and 15 years.

Impairment of Long-Lived Assets

The Company assesses potential impairments to its long-lived assets or asset groups, excluding goodwill which is separately tested for impairment, whenever events indicate that the carrying amount of such assets may not be recoverable. Long-lived assets are evaluated for impairment by comparing the carrying value of the asset or asset group with the estimated future net undiscounted cash flows expected to result from the use of the asset or asset group, including cash flows from disposition. If the future net undiscounted cash flows are less than the carrying value, an impairment loss is calculated. An impairment loss is determined by the amount that the asset’s or asset group’s carrying value exceeds its estimated fair value. Estimated fair value is generally measured by discounting estimated future cash flows. If an impairment loss is recognized, the adjusted balance becomes the new cost basis and is depreciated (amortized) over the remaining useful life. The Company also periodically reassesses the useful lives of its long-lived assets due to advances and changes in technologies.

In 2019, the Company incurred immaterial impairment charges related to certain long-lived assets removed from service during the year. In the fourth quarter of 2018, the Company recognized an impairment charge of $2.2 million related to developed technology. See Note 5. Goodwill and Other Intangibles for further discussion.

As a result of the recent COVID-19 pandemic and its impacts on the global economy, it is reasonably possible that the Company will be adversely impacted in future periods which may result in the recognition of material impairment charges related to its long-lived assets.

Goodwill

Goodwill represents the excess of the cost of an acquired business over the amounts assigned to the net acquired assets. Goodwill is not amortized but is tested for impairment at the reporting unit level, on an annual basis or more frequently, if events occur or circumstances change indicating potential impairment. The Company annually tests goodwill for impairment on October 1.

In evaluating goodwill for impairment, the Company may first assess qualitative factors to determine whether it is more likely than not (i.e., there is a likelihood of more than 50%) that the Company’s fair value is less than its carrying amount. Qualitative factors that the Company considers include, but are not limited to, macroeconomic and industry conditions, overall financial performance and other relevant entity-specific events. If the Company bypasses the qualitative assessment, or if the Company concludes that it is more likely than not that the fair value of a reporting unit is less than its carrying value, then the Company performs a two-step goodwill impairment test to identify potential goodwill impairment and measures the amount of goodwill impairment it will recognize, if any.

In the first step of the two-step goodwill impairment test, the Company compares the estimated fair value of the reporting unit with its related carrying value. The Company has two reporting units: PSI and Professional Power Products, Inc. (“3PI”). If the estimated fair value exceeds the carrying amount, no further analysis is needed. If, however, the reporting unit’s estimated fair value is less than its carrying amount, the Company proceeds to the second step and calculates the implied fair value of goodwill to determine whether any impairment is required.

The Company calculates its estimated fair value using the income and market approaches when feasible, or an asset approach when neither the income nor the market approach has sufficient data. For the income approach, a discounted cash flow method, the Company uses internally developed discounted cash flow models that include the following assumptions, among others: projections of revenues, expenses and related cash flows based on assumed long-term growth rates and demand trends, expected future investments to grow new units, and estimated discount rates. The Company based these assumptions on its historical data and experience, industry projections, and micro and macro general economic condition projections and expectations. The market approach, also called the Guideline Public Company Approach, compares the value of an entity to similar publicly traded companies. The asset approach estimates the selling price the unit could achieve under assumed market conditions.

If the fair value of a reporting unit exceeds its carrying amount, goodwill of the reporting unit is considered not impaired, and the second step of the impairment test is unnecessary. If the carrying amount of a reporting unit exceeds its fair value, the second step of the goodwill impairment test is performed to measure the amount of impairment loss, if any. The second step compares the implied fair value of the reporting unit goodwill with the carrying amount of that goodwill. If the carrying amount of reporting unit goodwill exceeds the implied fair value of that goodwill, an impairment loss is recognized in an amount equal to that excess.

During the years ended December 31, 2019 and 2018, the Company performed a Step 1 assessment and determined that the estimated fair value of the reporting units exceeded the carrying value; as such, no impairment charges were recognized.

Other Accrued Liabilities

Other accrued liabilities consisted of the following:



(in thousands)	As of December 31,
Other Accrued Liabilities	2019		2018
Accrued product warranty	$	17,142	$	9,767
Litigation reserves ^*	5,020		16,139
Contract liabilities	26,898		4,897
Accrued compensation and benefits	6,599		4,520
Operating lease liabilities	3,789		—
Accrued interest expense	1,087		1,175
Other	5,495		9,202
Total	$	66,030	$	45,700

As of December 31, 2019, litigation reserves primarily consisted of reserves related to ongoing government investigations and the settlement of the Federal Derivative Litigation. As of December 31, 2018, litigation reserves primarily consisted of accruals for the settlement of the Securities Litigation, Federal Derivative Litigation, and the Cohen matter. The Company concluded that insurance recovery was probable related to $1.9 million and $14.0 million of the litigation reserves as of December 31, 2019 and 2018, respectively, and recognized full recovery of the settlement amounts in Prepaid expenses and other current assets. See Note 10. Commitments and Contingencies for additional information.

Warranty Costs

The Company offers a standard limited warranty on the workmanship of its products that in most cases covers defects for a defined period. Warranties for certified emission products are mandated by the U.S. Environmental Protection Agency (the “EPA”) and / or the California Air Resources Board (the “CARB”) and are longer than the Company’s standard warranty on certain emission-related products. The Company’s products also carry limited warranties from suppliers. The Company’s warranties generally apply to engines fully manufactured by the Company and to the modifications the Company makes to supplier base products. Costs related to supplier warranty claims are generally borne by the supplier and passed through to the end customer.

Warranty estimates are based on historical experience and represent the projected cost associated with the product. A liability and related expense are recognized at the time products are sold. The Company adjusts estimates when it is determined that actual costs may differ from initial or previous estimates.

The Company records adjustments to preexisting warranties for changes in its estimate of warranty costs for products sold in prior fiscal years in the period in which new information is received and the information indicates that actual costs may differ from the Company’s initial or previous estimates. Such adjustments typically occur when claims experience deviates from historic and expected trends. During 2019, the Company recognized a charge for adjustments to preexisting warranties of $2.7 million compared to charges of $3.8 million in 2018.

When the Company identifies cost effective opportunities to address issues in products sold or corrective actions for safety issues, it initiates product recalls or field campaigns. As a result of the uncertainty surrounding the nature and frequency of product recalls and field campaigns, the liability for such actions is generally recorded when the Company commits to a product recall or field campaign. In each subsequent quarter after a recall or field campaign is initiated, the recorded warranty liability balance is analyzed, reviewed and adjusted, if necessary, to reflect any changes in the anticipated average cost of repair or number of repairs to be completed prospectively.

When collection is reasonably assured, the Company also estimates the amount of warranty claim recoveries to be received from its suppliers. Warranty costs and recoveries are included in Cost of sales in the Consolidated Statements of Operations.

Accrued product warranty activities are presented below:



(in thousands)	For the Year Ended December 31,
Accrued Product Warranty	2019			2018
Balance at beginning of year	$	23,102		$	12,628
Current year provision	10,349			15,840
Changes in estimates for preexisting warranties ^*	2,730			3,842
Payments made during the period	(10,680		)	(9,208		)
Balance at end of year	25,501			23,102
Less: Current portion	17,142			9,767
Noncurrent accrued product warranty	$	8,359		$	13,335

Change in estimates for preexisting warranties reflect changes in the Company’s estimate of warranty costs for products sold in prior periods. Such adjustments typically occur when claims experience deviates from historic and expected trends. The Company’s warranty liability is generally affected by failure rates, repair costs and the timing of failures. Future events and circumstances related to these factors could materially change the estimates and require adjustments to the warranty liability. In addition, new product launches require a greater use of judgment in developing estimates until historical experience becomes available. In the first quarter of 2019, the Company recorded a charge for changes in estimates of $2.7 million, or $0.13 per diluted share.

Revenue Recognition

On January 1, 2018, the Company adopted the new revenue recognition guidance, Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers (“ASC 606”), on a modified retrospective basis. See Note 2. Revenue for additional information the Company’s policy related to revenue recognition.

Recently Issued Accounting Pronouncements – Adopted

In February 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-02, Leases, which created ASC Topic 842, Leases, and superseded the existing guidance in ASC 840, Leases. See Note 7. Leases for additional information on the Company’s policy related to leases.

Recently Issued Accounting Pronouncements – Not Yet Adopted

In August 2018, the FASB issued ASU 2018-15, Intangibles – Goodwill and Other – Internal Use Software: Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. This guidance requires the use of existing accounting guidance applicable to software developed for internal use to be applied to cloud computing service contracts’ implementation costs. The costs capitalized would be amortized over the life of the agreement, including renewal option periods likely to be used. This guidance is effective for fiscal 2020, with early adoption permitted. The Company will adopt the standard effective January 1, 2020 on a prospective basis and does not anticipate that this guidance will have a material impact on its Consolidated Balance Sheet and Consolidated Statement of Operations.

In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement: Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement, which both reduces and expands selected disclosure requirements. The principal changes expected to impact the Company’s disclosure are requirements to disclose the range and weighted average of each of the significant unobservable items and the way the weighted average of a range is calculated for items in the “table of significant unobservable inputs.” The guidance also requires disclosure of changes in unrealized gains and losses in other comprehensive income and removes requirements regarding, among other items, disclosure of the valuation process for Level 3 measurements. This guidance is effective for fiscal 2020. The Company plans to implement the guidance when it becomes effective and does not currently anticipate that this guidance will have a material impact on its Consolidated Balance Sheet and Consolidated Statement of Operations.

In January 2017, the FASB issued ASU 2017-04, Intangibles – Goodwill and Other: Simplifying the Test for Goodwill Impairment, which eliminated the requirement to calculate the implied fair value of goodwill to measure a goodwill impairment charge. Instead, entities will record an impairment charge based on the excess of a reporting unit’s carrying amount over its fair value. The ASU is effective for annual and interim impairment tests performed in periods beginning after December 15, 2019; early adoption is permitted for annual and interim goodwill impairment testing dates after January 1, 2017. The amendments in this ASU are to be applied on a prospective basis. The Company currently plans on adopting the guidance on January 1, 2020 when it becomes effective and does not expect the guidance to have a material impact on its financial statements.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments, which applies primarily to the Company’s accounts receivable impairment loss allowances. The guidance provides a revised model whereby the current expected credit losses are used to compute impairment of financial instruments. The new model requires evaluation of historical experience and various current and expected factors, which may affect the estimated amount of losses and requires determination of whether the affected financial instruments should be grouped in units of account. The guidance, as originally issued, was effective for fiscal years beginning after December 15, 2019. In November 2019, the FASB issued ASU 2019-10, Financial Instruments – Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842) Effective Dates, which deferred the effective dates of these standards for certain entities. Based on the guidance, the effective date of ASU 2016-13 is deferred for the Company until fiscal year 2023. The Company currently plans to adopt the guidance on January 1, 2023 when it becomes effective. The Company is continuing to assess the impact of the standard on its financial statements.

Revenue

12 Months Ended

Dec. 31, 2019

Revenue from Contract with Customer [Abstract]

Revenue

Revenue Recognition

The Company determines the amount of revenue to be recognized through the following steps:


•	identification of the contract, or contracts with a customer;


•	identification of the performance obligations in the contract;


•	determination of the transaction price;


•	allocation of the transaction price to the performance obligations in the contract; and


•	recognition of revenue when, or as, the Company satisfies the performance obligations.

Revenue for the Company is generated from contracts that may include a single performance obligation (generally, a single type of engine) or multiple performance obligations (which may include an engine with aftermarket parts, different types of engines, etc.). A performance obligation is a promise in a contract to transfer a distinct good or service to the customer and is the unit of account for revenue recognition. Revenue is measured at the transaction price which is based on the amount of consideration that the Company expects to receive in exchange for transferring the promised goods or services to the customer. The transaction price is allocated to each distinct performance obligation and recognized as revenue when, or as, the performance obligation is satisfied. The Company is required to estimate the total consideration expected to be received from contracts with customers. The consideration expected to be received may be variable based on the specific terms of the contract and the Company’s past practices.

For contracts with multiple performance obligations, the Company allocates the total transaction price to distinct performance obligations based on directly observable data, if available, or the Company’s best estimate of the stand-alone selling price of each distinct performance obligation. The primary method used to estimate stand-alone selling price is the cost plus a margin approach.

The Company applies significant judgment in order to identify and determine the number of performance obligations, determine the total transaction price, allocate the transaction price to each performance obligation, and determine the appropriate timing of revenue recognition.

Taxes collected from customers and remitted to governmental authorities are presented on a net basis; that is, such taxes are excluded from revenues.

The Company’s payment terms are generally 60 days or less and its sales arrangements do not contain any significant financing components.

Timing of revenue recognition. The Company recognizes revenue related to performance obligations in its contracts with customers when control passes to the customer. Control passes to the customer when the customer has the ability to direct the use of and obtain substantially all of the remaining benefits from the asset. For the majority of the Company’s products, revenue is recognized at a point in time when the products are shipped or delivered to the customer based on the shipping terms as that is the point in time when control passes to the customer. For the years ended December 31, 2019 and 2018, the Company recognized revenue of $489.0 million and $449.8 million, respectively, related to products shipped or delivered at a point in time.

The Company also recognizes revenue over time primarily when the Company’s performance obligations include enhancing a customer-controlled asset (generally when an engine is provided by the customer), constructing an asset with no alternative future use and the Company has an enforceable right to payment throughout the period as the services are performed, or providing an extended warranty beyond the Company’s standard warranty. The Company recognizes revenue throughout the manufacturing process when constructing an asset based on labor hours incurred because the customer receives the benefit of the asset as the product is constructed. The Company believes labor hours incurred relative to total estimated labor hours at completion faithfully depicts the transfer of control to the customer. The Company recognizes revenue related to extended warranty programs based on the passage of time over the extended warranty period. For the years ended December 31, 2019 and 2018, the Company recognized revenue of $57.1 million and $46.2 million, respectively, for products manufactured over time.

Shipping and handling costs. The Company accounts for shipping and handling costs as fulfillment costs which are recorded in Cost of sales in the Consolidated Statements of Operations. This includes shipping and handling costs incurred after control of the asset has transferred to the customer as the Company has elected the practical expedient in ASC 606.

Variable consideration. Variable consideration primarily includes rebates and discounts. The Company estimates the projected amount of rebates and discounts based on current assumptions, customer-specific information and historical experience. Variable consideration is recorded as a reduction of revenue to the extent that it is probable that there will not be significant changes to the Company’s estimate of variable consideration when any uncertainties are settled.

Costs to obtain and fulfill a contract. The Company has elected the practical expedient in ASC 606 to recognize incremental costs to obtain a contract (primarily commissions) as expense when incurred since the amortization period of the asset that the Company otherwise would have recognized is one year or less.

Disaggregation of Revenue

The following table summarizes net sales by end market:



(in thousands)	For the Year Ended December 31,
End Market	2019		2018
Energy	$	222,779	$	185,685
Industrial	180,111		201,196
Transportation	143,186		109,157
Total	$	546,076	$	496,038

The following table summarizes net sales by geographic area:



(in thousands)	For the Year Ended December 31,
Geographic Area	2019		2018
North America	$	483,302	$	436,068
Pacific Rim	39,180		42,071
Europe	16,562		13,743
Other	7,032		4,156
Total	$	546,076	$	496,038

Contract Balances

Most of the Company’s contracts are for a period of less than one year; however, certain long-term manufacturing and extended warranty contracts extend beyond one year. The timing of revenue recognition may differ from the time of invoicing to customers and these timing differences result in contract assets, or contract liabilities on the Company’s Consolidated Balance Sheet. Contract assets include amounts related to the contractual right to consideration for completed performance when the right to consideration is conditional. The Company records contract liabilities when cash payments are received or due in advance of performance. Contract assets and contract liabilities are recognized at the contract level.



(in thousands)	As of December 31,
	2019			2018
Short-term contract assets (included in Prepaid expenses and other current assets)	$	694		$	2,926
Short-term contract liabilities (included in Other accrued liabilities)	(26,898		)	(4,897		)
Long-term contract liabilities (included in Noncurrent contract liabilities)	(17,998		)	(14,611		)
Net contract liabilities	$	(44,202	)	$	(16,582	)

During the year ended December 31, 2019, the Company recognized $6.7 million of revenue upon satisfaction of performance obligations related to amounts that were included in the net contract liabilities balance as of December 31, 2018. The increase in the contract liabilities from December 31, 2018 to December 31, 2019 is primarily related to the prepayment for certain engines by a customer under a long-term supply agreement.

Remaining Performance Obligations

The Company has elected the practical expedient to not disclose remaining performance obligations that have expected original durations of one year or less. For performance obligations that extend beyond one year, the Company had $41.8 million of remaining performance obligations as of December 31, 2019 primarily related to a long-term manufacturing contract with a customer and extended warranties. The Company expects to recognize revenue related to these remaining performance obligations of approximately $23.8 million in 2020, $15.6 million in 2021, $0.7 million in 2022, $0.7 million in 2023 and $1.0 million in 2024 and beyond.

Weichai Transactions

12 Months Ended

Dec. 31, 2019

Equity [Abstract]

Weichai Transactions

In March 2017, the Company and Weichai executed the SPA in which the Company issued stock and a warrant to Weichai for aggregate proceeds of $60.0 million (the “Weichai Transactions”), composed of the following:


•	2,728,752 shares of Common Stock;


•	2,385,624 shares of Series B Redeemable Convertible Preferred Stock (“Series B Convertible Preferred Stock”) that was converted into 4,771,248 shares of Common Stock in November 2017; and


•	the Weichai Warrant as discussed further below.

The Company used proceeds from the sale of the above securities pursuant to the SPA and borrowings under the Wells Fargo Credit Agreement to pay off the outstanding TPG Term Loan (the “TPG Term Loan”) with TPG Specialty Lending, Inc. (“TPG”).

Weichai Warrant

In September 2018, the Weichai Warrant was amended under the terms of a second amended and restated warrant (“Amended and Restated Warrant”) to defer its exercise date to a 90-day period commencing April 1, 2019, to adjust the exercise price to a price per share of the Company’s Common Stock equal to the lesser of (i) 50% of the Volume-Weighted Average Price (“VWAP”) during the 20 consecutive trading day period preceding October 1, 2018 and (ii) 50% of the VWAP during the 20 consecutive trading day period preceding the date of exercise, subject to an adjustment that could reduce the exercise price by up to $15.0 million. In the event that the adjustment exceeded the exercise price, the excess would be due to the warrant holder.

On April 23, 2019, Weichai exercised the Weichai Warrant resulting in the Company issuing 4,049,759 shares of the Company’s Common Stock and Weichai becoming the owner of 51.5% of the outstanding shares of the Company’s Common Stock, as of such date. The exercise proceeds for the warrants of $1.6 million were based on 50% of the VWAP during the 20 consecutive trading day period preceding April 23, 2019 and the $15.0 million reduction in the exercise price described above. The Company recorded net expense of $1.4 million related to the Weichai Warrant during 2019 including the impact of the exercise.

Weichai Collaboration Arrangement and Related Party Transactions

The Company and Weichai executed a strategic collaboration agreement (the “Collaboration Agreement”) on March 20, 2017, in order to achieve their respective strategic objectives and enhance the strategic cooperation alliance to share experiences, expertise and resources. Among other things, the collaboration arrangement established a joint steering committee, permitted Weichai to second a limited number of certain technical, marketing, sales, procurement and finance personnel to work at the Company and established several collaborations, related to stationary natural-gas applications and Weichai diesel engines. The collaboration arrangement provided for the steering committee to create various sub-committees with operating roles and otherwise governs the treatment of intellectual property of parties prior to the collaboration and the intellectual property developed during the collaboration. The Collaboration Agreement had a term of three years that was set to expire in March 2020. On March 26, 2020, the Collaboration Agreement was extended for an additional term of three years.

The Company evaluates whether an arrangement is a collaborative arrangement at its inception based on the facts and circumstances specific to the arrangement. The Company also reevaluates whether an arrangement qualifies or continues to qualify as a collaborative arrangement whenever there is a change in either the roles of the participants or the participants’ exposure to significant risks and rewards dependent on the ultimate commercial success of the endeavor. For those collaborative arrangements where it is determined that the Company is the principal participant, costs incurred and revenue generated from third parties are recorded on a gross basis in the financial statements. For the years ended December 31, 2019 and 2018, the Company sales to and outstanding receivables from Weichai were immaterial. The Company purchased $4.4 million and $3.5 million of inventory from Weichai during 2019 and 2018, respectively. As of December 31, 2019 and 2018, the Company had outstanding payables to Weichai of $5.9 million and $3.7 million, respectively.

Stockholders’ Equity

Common and Treasury Stock

The changes in shares of Common and Treasury Stock are as follows:



(in thousands)	Common Shares Issued	Treasury Stock Shares		Common Shares Outstanding
Balance as of December 31, 2017	19,067	634		18,433
Net shares issued for stock awards	—	(205	)	205
Balance as of December 31, 2018	19,067	429		18,638
Net shares issued for Stock awards	—	(169	)	169
Shares issued to Weichai	4,050	—		4,050
Balance as of December 31, 2019	23,117	260		22,857

Preferred Stock

The Company is authorized to issue 5,000,000 shares of Preferred stock, par value $0.001 per share. The Preferred stock may be designated into one or more series as determined by the Board. As of December 31, 2019, the Board had authorized two series of Preferred stock. At December 31, 2019 and 2018, there were no shares of Preferred stock outstanding.

Weichai Warrant

Property, Plant and Equipment

12 Months Ended

Dec. 31, 2019

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Property, plant and equipment by type were as follows:



(in thousands)	As of December 31,
Property, Plant and Equipment	2019			2018
Leasehold improvements	$	6,745		$	6,405
Machinery and equipment	41,243			38,454
Construction in progress	1,679			1,241
Total property, plant and equipment, at cost	49,667			46,100
Accumulated depreciation	(26,473		)	(21,834		)
Property, plant and equipment, net	$	23,194		$	24,266

In April 2018, the Company finalized the purchase of emissions testing assets and the sublease of an emissions testing facility from Ricardo, Inc., a subsidiary of the strategic engineering and environmental consultancy, Ricardo Plc., for $5.6 million in cash. The Company accounted for the acquisition as an asset acquisition and recorded property, plant and equipment of $6.9 million, included within machinery and equipment in the table above, and an asset retirement obligation of $1.3 million as a result of the transaction. The fair value of the asset retirement obligation was estimated using Level 3 inputs. The asset retirement obligation is recorded in Other noncurrent liabilities in the Company’s Consolidated Balance Sheets.

Goodwill and Other Intangibles

12 Months Ended

Dec. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Other Intangibles

Goodwill

The carrying amount of goodwill at both December 31, 2019 and 2018 was $29.8 million. Accumulated impairment losses at both December 31, 2019 and 2018 were $11.6 million.

Other Intangible Assets

In March 2018, the Company acquired intellectual property (“IP”) from AGA Systems, LLC (“AGA”) for the conversion of certain gasoline engines to alternative fuel engines. The Company paid cash of $1.5 million ($1.0 million in 2018 and $0.5 million in 2017) to acquire the IP assets and provided a minimum guaranteed payment of an additional $1.2 million to be paid over a three-year period from the date of acquisition. If certain milestones related to future sales are met, the Company could pay up to an additional $3.3 million to AGA. The acquisition was accounted for as an asset acquisition because the gross assets acquired were concentrated within a group of similar identifiable assets. The Company recorded developed technology of $2.7 million related to the acquired IP and a liability of $1.2 million related to the guaranteed payment. The sales-based milestone payments are recorded as they are earned and the milestones are probable of being achieved. The developed technology was being depreciated over an estimated useful life of approximately three years. In the fourth quarter of 2018, based on uncertainty of the market for the conversion of certain gasoline engines to alternative fuel engines, the Company concluded that the forecasted future cash flows were not sufficient to recover the carrying value of the assets. As a result, the Company recorded an impairment charge of $2.2 million to write off the remaining book value of the intangible assets.

Components of intangible assets are as follows:



(in thousands)	As of December 31, 2019
	Gross Carrying Value		Accumulated Amortization			Net Book Value
Customer relationships	$	34,940	$	(22,236	)	$	12,704
Developed technology	700		(605		)	95
Trade names and trademarks	1,700		(1,127		)	573
Total	$	37,340	$	(23,968	)	$	13,372



(in thousands)	As of December 31, 2018
	Gross Carrying Value		Accumulated Amortization			Net Book Value
Customer relationships	$	34,940	$	(18,816	)	$	16,124
Developed technology	700		(537		)	163
Trade names and trademarks	1,700		(977		)	723
Total	$	37,340	$	(20,330	)	$	17,010

Estimated future amortization expense for intangible assets as of December 31, 2019 is as follows:



(in thousands)
Year Ending December 31,	Estimated Amortization
2020	$	3,053
2021	2,535
2022	2,124
2023	1,746
2024	1,459
2025 and beyond	2,455
Total	$	13,372

Debt

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Debt

The Company’s outstanding debt consisted of the following:



(in thousands)	As of December 31,
	2019			2018
Short-term financing:
Wells Fargo revolving credit facility	$	39,527		$	54,613

Long-term debt:
Unsecured senior notes	$	55,000		$	55,000
Finance leases and other debt	1,087			456
Unamortized debt issuance costs ^*	(235		)	(288		)
Total long-term debt and finance leases	55,852			55,168
Less: Current maturities of long-term debt and finance leases	195			80
Long-term debt	$	55,657		$	55,088


*	Unamortized financing costs and deferred fees on the Wells Fargo Revolving Credit Facility are not presented in the above table as they are classified in Prepaid expenses and other current assets on the Consolidated Balance Sheets. Debt issuance costs incurred, including gross waiver fees (primarily paid to the lenders), were $0.3 million and $1.0 million in 2019 and 2018, respectively.

The Company paid $6.9 million and $6.1 million in cash for interest in 2019 and 2018, respectively.

The Company’s debt includes restrictive covenants that, if not met, could lead to renegotiation of its revolving credit facility, notes and indentures, a requirement to repay the Company’s borrowings and/or a significant increase in the cost of financing. These restrictive covenants may include, among other items, financial covenants pertaining to availability, permitted indebtedness, restrictions on dividends and various events of default.

Certain events of default (including delinquent filing of annual and periodic reports with the Securities and Exchange Commission (“SEC”) and material weaknesses in the control environment) occurred with respect to the Company’s credit agreements. While waivers were obtained or debt was renegotiated with the respective lenders, absent such waivers the debt would have been in breach of covenants. The Company pledged substantially all of its tangible and intangible assets, including inventory, receivables and fixed assets, as collateral under the Wells Fargo Credit Agreement.

Wells Fargo Credit Agreement

In June 2013, the Company entered into the Wells Fargo Credit Agreement. The Wells Fargo Credit Agreement enabled the Company to borrow under a revolving credit facility secured by substantially all of the Company’s tangible and intangible assets, including inventory, receivables and fixed assets. The Wells Fargo Credit Agreement has been amended several times since June 28, 2013, including in June 2016 when the agreement was amended and restated. Below are some of the current key terms of the Wells Fargo Credit Agreement:


•	matures on the earlier of March 31, 2021 or 60 days prior to the final maturity of the Unsecured Senior Notes (which currently mature on June 30, 2020 resulting in a current maturity date of May 1, 2020 for the Wells Fargo Credit Agreement);


•	includes a maximum $75.0 million revolving line of credit to the Company less a reserve of $9.0 million;


•	bears interest at Wells Fargo’s prime rate plus a margin ranging from 1.25% to 1.75% per annum or at the London Interbank Offered Rate (“LIBOR”) plus a margin ranging from 2.75% to 3.25% per annum at the Company’s option; interest rate margin will decrease by 1% per annum upon the Company becoming current with its SEC filings;


•	has an unused line fee of 0.25%;


•	contains restrictive covenants that, among other things, limit the ability of the Company and its subsidiaries to incur additional debt, prepay subordinated indebtedness, or make certain distributions on capital stock; and


•	limits borrowings to the lesser of the maximum revolving line of credit and the borrowing base, which is defined as a percentage of the Company’s eligible accounts receivable and inventory.

Information regarding amounts borrowed under the Wells Fargo Credit Agreement includes the following:



(in thousands, except interest rate)	Year ended December 31,
Description	2019			2018
Average borrowings under Wells Fargo Revolving Credit Facility	$	48,235		$	47,031
Average Interest Cost on Wells Fargo Revolving Credit Facility	6.30		%	6.51		%



(in thousands, except interest rate)	As of December 31,
Description	2019			2018
Accrued and unpaid interest	$	400		$	174
LIBOR loan interest rate	5.00		%	5.97		%
Wells Fargo Prime Rate (Base Rate) loan interest rate	6.25		%	7.25		%

As of December 31, 2019 and 2018, the Company had available borrowing capacity under the revolving line of credit of $14.9 million and $8.9 million, respectively.

Significant changes to the Wells Fargo Credit Agreement since January 1, 2018 are summarized in the table below:



Amendment Date and Title	Reason for Amendment	Significant Changes/Notes Regarding Amendment to the Wells Fargo Credit Agreement
March 29, 2018. Sixth Amendment and Waiver to the June 28, 2016 Agreement	To consider implications of various events of default	• Increased the maximum borrowing under the revolving credit facility to $75.0 million from $65.0 million • Modified the reserve against the maximum borrowing under the revolving credit facility to the greater of $6.5 million and 10% of borrowing base, but no more than $7.5 million on or prior to September 30, 2018 and thereafter equal to $9.0 million • Extended the maturity date of the facility to the earlier of March 31, 2021 or 60 days prior to the final maturity of the Unsecured Senior Notes, which were extended to January 1, 2020, resulting in a maturity date of November 2, 2019 on the Wells Fargo revolving credit facility • The revolving credit facility will continue to bear interest at a per annum rate equal to 100 basis points (1%) above the per annum rate otherwise applicable under the credit agreement until the Company is current with its SEC filings • The Company paid an amendment fee of $0.8 million.
May 16, 2019. Waiver to the June 28, 2016 Agreement	To consider implications of various events of default	• Waived any defaults that would arise from the failure to timely deliver annual audited financial statements for the fiscal year ended December 31, 2018 and the associated compliance certificate and the information required with it; provided that the financial statements and compliance certificate were delivered on or before December 31, 2019.

The aforementioned amendments, consents and waivers related to the Wells Fargo Credit Agreement in 2019 and 2018 were accounted for as debt modifications. There were no debt issuance costs or third-party fees incurred in 2019 related to the debt modifications during the year. The Company incurred fees of $0.8 million in 2018 related to the modification which were deferred and amortized through the anticipated maturity date of the Wells Fargo Credit Agreement. As of December 31, 2019, all deferred debt issuance costs related to the Wells Fargo Credit Agreement had been amortized.

The Wells Fargo revolving credit facility is presented as a current liability on the Consolidated Balance Sheets as of December 31, 2019 and 2018 because of a subjective acceleration clause and a “lockbox” arrangement that sweeps cash receipts to pay down the revolver balance, without requiring the Company’s specific consent, and provides advances up to current limits to cover outlays.

Unsecured Senior Notes

In April 2015, the Company entered into an agreement with certain institutional investors for a private sale of its Unsecured Senior Notes for the aggregate amount of $55.0 million with an interest rate of 5.50% per annum. Concurrently, in connection with the issuance of the Unsecured Senior Notes, the Company entered into an indenture agreement (“Indenture”), by and among the Company and its subsidiaries as guarantors and the Bank of New York Mellon, as Trustee. The Company received net proceeds of $53.5 million after financing costs of $1.5 million. As discussed previously in Note 1. Summary of Significant Accounting Policies and Other Information, the Company has presented issuance costs associated with its Unsecured Senior Notes as a direct deduction from the carrying value of the obligation on its Consolidated Balance Sheets.

The Unsecured Senior Notes are unsecured debt of the Company and are effectively subordinated to its existing and future secured debt, including the debt in connection with the Wells Fargo Credit Agreement. The following are some of the current key provisions of the Unsecured Senior Notes:


•	mature on June 30, 2020;


•	accrue interest at 7.50% per annum (reduced from 8.50% upon filing the 2017 Annual Report on Form 10-K in May 2019), payable semiannually in arrears on May 1 and November 1 of each year;


•	redeemable by the holders in whole or in part upon a change in control at a purchase price of 101% of the principal amount, plus accrued and unpaid interest;


•	contain restrictive covenants that, among other things, limit the ability of the Company and its subsidiaries to incur additional debt, prepay subordinated indebtedness, pay dividends or make other distributions on capital stock; and


•	provide for customary events of default (subject in certain cases to customary grace and cure periods).

Significant amendments to the Unsecured Senior Notes since January 1, 2018 are included in the table below:



Amendment Date and Title	Reason for Amendment	Significant Changes/Notes Related to Amendment to the Unsecured Senior Notes
April 19, 2018. Fourth Supplemental Indenture	To amend certain covenants and waive certain events of default	• Extended the maturity date to January 1, 2020 • Waived defaults with respect to the failure to file with the Trustee and the SEC for 2015 through 2019 • Increased the interest rate from 6.50% to 8.50% per annum effective October 1, 2018. The interest rate decreased to 7.50% per annum upon filing the 2017 Form 10-K with the SEC • the Company paid a consent fee of $0.3 million.
October 30, 2019. Fifth Supplemental Indenture	To extend the maturity date	• Extended maturity date to June 30, 2020 • The Company paid a fee of $0.3 million

Debt issuance costs of $0.3 million and $0.3 million incurred in 2019 and 2018, respectively, were deferred and amortized to interest expense through the anticipated maturity date of the Unsecured Senior Notes.

The interest rate on the Unsecured Senior Notes decreased to 7.50% per annum upon filing the 2017 Form 10-K with the SEC in May 2019. In addition, on October 30, 2019, the maturity date of the Unsecured Senior Notes was extended to June 30, 2020. By extending the maturity date of the Unsecured Senior Notes, the maturity date of the Wells Fargo Credit Agreement is extended to May 1, 2020.

The Unsecured Senior Notes are presented as a noncurrent liability on the Consolidated Balance Sheets as of December 31, 2019 and 2018. As of December 31, 2019 and 2018, the accrued, but unpaid, interest on the Unsecured Senior Notes was $0.7 million and $0.8 million, respectively.

Credit Agreement

On April 2, 2020, the Company closed on its new senior secured revolving credit facility pursuant to the Credit Agreement with Standard Chartered. The Credit Agreement allows the Company to borrow up to $130.0 million and matures on March 26, 2021 with an optional 60-day extension subject to certain conditions and payment of a 0.25% extension fee. Borrowings under the Credit Agreement shall bear interest at either the alternate base rate or LIBOR plus 2.00%, and the Company is required to pay a 0.25% commitment fee on the average daily unused portion of the revolving credit facility under the Credit Agreement. The Credit Agreement is secured by substantially all of the Company’s assets and includes certain financial covenants as well as a change of control provision. On April 2, 2020, the Company borrowed $95.0 million under the Credit Agreement and utilized the funds to (i) repay the outstanding balance of $16.8 million under the Wells Fargo Credit Agreement, (ii) fully redeem and discharge $55.0 million in aggregate principal amount of the Unsecured Senior Notes and pay related interest and (iii) for general corporate purposes. The Wells Fargo Credit Agreement was terminated in connection with the repayment of the outstanding balance. The Company will recognize a loss on the extinguishment of the Wells Fargo Credit Agreement and the Unsecured Senior Notes of $0.1 million related to unamortized debt issuance costs and will defer additional debt issuance costs related to the closing of the Credit Agreement of $2.0 million. The Wells Fargo Credit Agreement maturity date was the earlier of March 31, 2021, or 60 days prior to the final maturity of the Unsecured Senior Notes, which were to mature on June 30, 2020, resulting in a maturity date of May 1, 2020 for the Wells Fargo Credit Agreement.

The below schedule of remaining maturities of long-term debt excludes finance leases (refer to Note 7. Leases) and additional debt drawn under the Credit Agreement in April 2020 but reflects the Unsecured Senior Notes as due in 2021 due to the execution of the Credit Agreement in April 2020 and refinancing of the Unsecured Senior Notes.



(in thousands)
Year Ending December 31,	Maturities of Long-Term Debt
2020	$	107
2021	55,107
2022	101
2023	91
2024	91
Total	$	55,497

Leases

12 Months Ended

Dec. 31, 2019

Leases [Abstract]

Leases

On January 1, 2019, the date of initial application, the Company adopted ASC 842 using the modified retrospective transition method whereby prior comparative periods have not been restated and continue to be reported under the accounting standards in effect for the prior period. The Company elected the package of practical expedients permitted under the transition guidance for all leases, which allowed the Company to adopt ASC 842 without reassessing whether arrangements contain leases, the lease classification, and the determination of initial direct costs.

Upon adoption on January 1, 2019, the Company recognized right-of-use (“ROU”) assets inclusive of finance leases, net of prepaids, incentives, and impairments, of $24.6 million and lease liabilities of $25.1 million in the Consolidated Balance Sheet. At adoption, there was no impact to the Consolidated Statement of Operations, Consolidated Statement of Cash Flows or Consolidated Statement of Stockholders’ Equity (Deficit).

Lease Policies

The Company determines if an arrangement contains a lease in whole or in part at the inception of the contract. ROU assets represent the right to use an underlying asset for the lease term while lease liabilities represent the obligation to make lease payments arising from the lease. All leases with an expected term greater than twelve months result in the recognition of a ROU asset and a liability at the lease commencement date based on the present value of the lease payments over the lease term. The Company uses its incremental borrowing rate based on the information available at the lease commencement date to determine the present value of the lease payments unless the implicit rate in the lease is readily determinable. The incremental borrowing rate is determined considering factors such as the lease term, the Company’s credit standing and the economic environment of the location of the lease.

The lease term includes all non-cancellable periods and may include options to extend (or to not terminate) the lease when it is reasonably certain that the Company will exercise the option. Leases that have a term of 12 months or less at the commencement date are expensed on a straight-line basis over the lease term and do not result in the recognition of a ROU asset or lease liability.

The Company classifies leases as finance leases when (i) there is a transfer of ownership of the underlying asset by the end of the lease term, (ii) the lease contains an option to purchase the asset that the Company is reasonably certain will be exercised, (iii) the lease term is for the majority of the remaining economic life of the asset, or (iv) the present value of the lease payments and any residual value guarantee equals or substantially exceeds the fair value of the asset.

Lease expense for operating leases is recognized on a straight-line basis over the lease term. Lease expense for finance leases is generally front-loaded as the finance lease ROU asset is depreciated on a straight-line basis, but interest expense on the lease liability is recognized using the interest method which results in more expense during the early years of the lease. Variable lease payments are expensed in the period in which the obligation for those payments is incurred. The Company has elected to combine lease and non-lease components, such as fixed maintenance costs, as a single lease component in calculating ROU assets and lease liabilities for all classes of leased assets.

Leases

The Company has obligations under lease arrangements primarily for facilities, equipment and vehicles. These leases have original lease periods expiring between March 2020 and August 2039. For the year ended December 31, 2019, the Company recorded lease expense of $6.9 million within Cost of sales, $0.7 million within Research, development and engineering, $0.3 million within SG&A and less than $0.1 million within Interest expense on the Consolidated Statement of Operations.

The following table summarizes the components of lease expense:



(in thousands)	For the Year Ended December 31,
	2019
Operating lease cost	$	5,472
Finance lease cost:
Amortization of ROU asset	170
Interest expense	49
Short-term lease cost	492
Variable lease cost	1,675
Total lease cost	$	7,858

For the year ended December 31, 2018, rent expense related to operating leases under previous accounting guidance was $5.1 million.

The following table presents supplemental cash flow information related to leases:



(in thousands)	For the Year Ended December 31,
	2019
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows paid for operating leases	$	5,181
Operating cash flows paid for interest portion of finance leases	49
Financing cash flows paid for principal portion of finance leases	152
Right-of-use assets obtained in exchange for lease obligations
Operating leases	280
Finance leases	536

As of December 31, 2019, the weighted-average remaining lease term was 6.7 years for operating leases and 4.5 years for finance leases. The weighted-average discount rate was 7.2% for operating leases and 6.8% for finance leases. The following table presents supplemental balance sheet information related to leases as of December 31, 2019:



(in thousands)	Operating Leases		Finance Leases
ROU assets, net ¹	$	20,677	$	777

Lease liabilities, current ²	3,789		195
Lease liabilities, non-current ³	17,679		617
Total lease liabilities	$	21,468	$	812

1. Included in Other noncurrent assets for operating leases and Property, plant and equipment, net for finance leases on the Consolidated Balance Sheet.

2. Included in Other accrued liabilities for operating leases and Current maturities of long-term debt for finance leases on the Consolidated Balance Sheet.


3.	Included in Other noncurrent liabilities for operating leases and Long-term debt, net of current maturities for finance leases on the Consolidated Balance Sheet.

The following table presents maturity analysis of lease liabilities as of December 31, 2019:



(in thousands)
Year Ending December 31,	Operating Leases		Finance Leases
2020	$	5,210	$	243
2021	4,827		243
2022	4,668		175
2023	3,247		101
2024	1,813		82
Thereafter	7,389		96
Total undiscounted lease payments	27,154		940
Less: imputed interest	5,686		128
Total lease liabilities	$	21,468	$	812

The future minimum lease payments due under operating and capital leases in effect, as amended and extended, as of December 31, 2018, under the previous lease guidance, were as follows:



(in thousands)	Operating		Capital
2019	$	5,071	$	80
2020	5,175		63
2021	4,724		67
2022	4,681		50
2023	3,104		13
2024 and beyond	3,694		—
Total	$	26,449	$	273

Leases

Lease Policies

Leases

The following table summarizes the components of lease expense:



(in thousands)	For the Year Ended December 31,
	2019
Operating lease cost	$	5,472
Finance lease cost:
Amortization of ROU asset	170
Interest expense	49
Short-term lease cost	492
Variable lease cost	1,675
Total lease cost	$	7,858

For the year ended December 31, 2018, rent expense related to operating leases under previous accounting guidance was $5.1 million.

The following table presents supplemental cash flow information related to leases:



(in thousands)	For the Year Ended December 31,
	2019
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows paid for operating leases	$	5,181
Operating cash flows paid for interest portion of finance leases	49
Financing cash flows paid for principal portion of finance leases	152
Right-of-use assets obtained in exchange for lease obligations
Operating leases	280
Finance leases	536



(in thousands)	Operating Leases		Finance Leases
ROU assets, net ¹	$	20,677	$	777

Lease liabilities, current ²	3,789		195
Lease liabilities, non-current ³	17,679		617
Total lease liabilities	$	21,468	$	812

1. Included in Other noncurrent assets for operating leases and Property, plant and equipment, net for finance leases on the Consolidated Balance Sheet.

2. Included in Other accrued liabilities for operating leases and Current maturities of long-term debt for finance leases on the Consolidated Balance Sheet.


3.	Included in Other noncurrent liabilities for operating leases and Long-term debt, net of current maturities for finance leases on the Consolidated Balance Sheet.

The following table presents maturity analysis of lease liabilities as of December 31, 2019:



(in thousands)
Year Ending December 31,	Operating Leases		Finance Leases
2020	$	5,210	$	243
2021	4,827		243
2022	4,668		175
2023	3,247		101
2024	1,813		82
Thereafter	7,389		96
Total undiscounted lease payments	27,154		940
Less: imputed interest	5,686		128
Total lease liabilities	$	21,468	$	812

The future minimum lease payments due under operating and capital leases in effect, as amended and extended, as of December 31, 2018, under the previous lease guidance, were as follows:



(in thousands)	Operating		Capital
2019	$	5,071	$	80
2020	5,175		63
2021	4,724		67
2022	4,681		50
2023	3,104		13
2024 and beyond	3,694		—
Total	$	26,449	$	273

Fair Value of Financial Instruments

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

For assets and liabilities measured at fair value on a recurring and nonrecurring basis, a three-level hierarchy of measurements based upon observable and unobservable inputs is used to arrive at fair value. Observable inputs are developed based on market data obtained from independent sources, while unobservable inputs reflect the Company’s assumptions about valuation based on the best information available in the circumstances. Depending on the inputs, the Company classifies each fair-value measurement as follows:


•	Level 1 – based on quoted prices in active markets for identical assets or liabilities;


•	Level 2 – based on other significant observable inputs for the assets or liabilities through corroborations with market data at the measurement date; and


•	Level 3 – based on significant unobservable inputs that reflect management’s best estimate of what market participants would use to price the assets or liabilities at the measurement date.

Financial Instruments Measured at Carrying Value

Current Assets

Cash and cash equivalents are measured at carrying value, which approximates fair value because of the short-term maturities of these instruments.

Debt

The Company measures the Wells Fargo Credit Agreement and the Unsecured Senior Notes at original carrying value including accrued interest, net of unamortized deferred financing costs and fees. The fair value of the revolving credit facility approximates carrying value, as it consists of short-term variable rate loans.

The fair value measurement of the Unsecured Senior Notes is defined as Level 3 in the three-level fair value hierarchy, as the inputs to their valuation are not all market observable.



(in thousands)	As of December 31, 2019
	Carrying Value		Fair Value
	Carrying Value		Level 1		Level 2		Level 3
Wells Fargo Credit Agreement	$	39,527	$	—	$	39,527	$	—
Unsecured Senior Notes	54,765		—		—		54,600



(in thousands)	As of December 31, 2018
	Carrying Value		Fair Value
	Carrying Value		Level 1		Level 2		Level 3
Wells Fargo Credit Agreement	$	54,613	$	—	$	54,613	$	—
Unsecured Senior Notes	54,712		—		—		52,700

Other Financial Assets and Liabilities

In addition to the methods and assumptions used for the financial instruments discussed above, accounts receivable, net, income tax receivable, and accounts payable and certain accrued expenses are measured at carrying value, which approximates fair value because of the short-term maturities of these instruments.

Financial Instruments Measured at Fair Value

The Company’s warrant liability was measured at fair value based on unobservable inputs and was, thus, considered a Level 3 financial instrument in the three-level valuation hierarchy.



(in thousands)	As of December 31, 2018
	Carrying Value		Fair Value
	Carrying Value		Level 1		Level 2		Level 3
Warrant liability	$	35,100	$	—	$	—	$	35,100

Warrants

The following table summarizes changes in the estimated fair value of the Company’s warrant liability:



(in thousands)	As of December 31,
	2019			2018
Balance at beginning of year	$	35,100		$	24,700
Change in value of warrants ^*	1,352			10,400
Settlement of warrants	(36,452		)	—
Balance at end of year	$	—		$	35,100


*	The change in value of the warrant liability for each year is presented in Loss from change in value and exercise of warrants in the Company’s Consolidated Statements of Operations. The change in value for the year ended December 31, 2019 includes the impact of Weichai exercising the warrant in April 2019.

Weichai Warrant Liability

The Company estimated the fair value of the Weichai Warrant financial instrument using a publicly traded stock pricing approach with a Black-Scholes option pricing model and a Monte Carlo simulation. Given the unobservable nature of the inputs to the pricing models, the Weichai Warrant was classified as a Level 3 instrument.

The inputs of the Black-Scholes option pricing model were as follows:



Assumptions	As of December 31,
Assumptions	2018
Market value of the Common Stock	$	9.25
Exercise price	varies
Risk-free interest rate	2.6		%
Estimated price volatility	55.0		%
Contractual term	0.5 years

The estimated price volatility represents the upper end of the range of implied volatility of publicly traded call options of benchmark companies.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Defined Contribution Plans	12 Months Ended
Defined Contribution Plans	Dec. 31, 2019
Retirement Benefits [Abstract]
Defined Contribution Plans	Defined Contribution Plans As of December 31, 2018, the Company had not contributed to the plans and recorded a liability of $0.7 million for 2018 contributions. During 2019, the Company made contributions of $0.7 million (primarily related to the contribution for 2018) and had recorded a liability of $0.5 million as of December 31, 2019 for additional 2019 contributions.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2019

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Legal Contingencies

The legal matters discussed below and others could result in losses, including damages, fines, civil penalties and criminal charges, which could be substantial. The Company records accruals for these contingencies to the extent the Company concludes that a loss is both probable and reasonably estimable. Regarding the matters disclosed below, unless otherwise disclosed, the Company has determined that liabilities associated with these legal matters are reasonably possible; however, unless otherwise stated, the possible loss or range of possible loss cannot be reasonably estimated. Given the nature of the litigation and investigations and the complexities involved, the Company is unable to reasonably estimate a possible loss for all such matters until the Company knows, among other factors the following information:


•	what claims, if any, will survive dispositive motion practice;


•	the extent of the claims, particularly when damages are not specified or are indeterminate;


•	how the discovery process will affect the litigation;


•	the settlement posture of the other parties to the litigation; and


•	any other factors that may have a material effect on the litigation or investigation.

However, the Company could incur judgments, enter into settlements or revise its expectations regarding the outcome of certain matters, and such developments could have a material adverse effect on the Company’s results of operations in the period in which the amounts are accrued and/or liquidity in the period in which the amounts are paid.

Securities and Exchange Commission and United States Attorney’s Office for the Northern District of Illinois Investigations

In August 2016, the Chicago Regional Office of the SEC commenced an investigation focused on, among other things, the Company’s financial reporting, misapplication of U.S. GAAP, revenue recognition practices and related conduct, which resulted in the accounting errors giving rise to the financial restatements reported in prior SEC filings. In 2016, the United States Attorney's Office for the Northern District of Illinois (the “USAO”) began conducting a parallel investigation regarding these matters. The Company is fully cooperating with the SEC and the USAO in their investigations. The Company is engaged in ongoing discussions with the SEC and the USAO regarding resolutions of these matters. If the SEC or the USAO determines that the Company violated federal securities or other laws and institutes civil enforcement or criminal proceedings, the Company may become subject to civil or criminal sanctions, including, but not limited to, criminal or civil charges, fines, other monetary penalties, injunctive relief and compliance conditions imposed by a court or agreement, which may have a material adverse effect on the financial condition, results of operations or cash flows of the Company.

Securities Litigation

In August 2016, Sumit Gupta filed a putative stockholder class-action complaint against the Company, Gary S. Winemaster, Michael P. Lewis and Daniel P. Gorey in the U.S. District Court for the Northern District of Illinois (the “Gupta Action”). The complaint alleged violations of Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”) arising from public filings made between May 2015 and August 2016. In October 2016, Peter Stout initiated a second suit, asserting similar claims against the same defendants (the “Stout Action”).

In January 2017, the court consolidated the Gupta Action and the Stout Action and appointed Richard Giunta as lead plaintiff. The consolidated case is captioned Giunta v. Power Solutions International, Inc., No. 1:16-cv-09599 (N.D. Ill.) (the “Giunta Action”). The plaintiffs then filed an Amended Class Action Complaint (the “Amended Complaint”) against the Company and certain current and former officers and directors. The Amended Complaint alleges violations of Sections 10(b) and 20(a) of the Exchange Act arising from public filings, press releases and conference calls between February 2014 and February 2017. In January 2019, the parties executed a Stipulation and Agreement of Settlement (the “Settlement”) to resolve the Giunta Action. Under the terms of the Settlement, a payment of $8.5 million would be made by the Company and/or its insurers in exchange for the release of claims against the defendants and other released parties by the lead plaintiff and all settlement class members and for the dismissal of the Giunta Action with prejudice. The payment of the $8.5 million was placed into escrow by the Company’s insurers in February 2019. In May 2019, the court granted final approval of the settlement. The Company accrued for the settlement in Other accrued liabilities and for the full insurance recovery of the settlement amount in Prepaid expenses and other current assets as of December 31, 2018. See Note 1. Summary of Significant Accounting Policies and Other Information for additional information related to the Company’s insurance proceeds receivable and litigation reserves. No further action or impact to the Company’s results of operations, financial condition or cash flows is expected.

Federal Derivative Litigation

In February 2017, Travis Dorvit filed a putative stockholder derivative action in the U.S. District Court for the Northern District of Illinois, captioned Dorvit v. Winemaster, et al., No. 1:17-cv-01097 (N.D. Ill.) (the “Dorvit Action”), against certain of the Company’s current and former officers and directors. The complaint asserted claims for breach of fiduciary duty and unjust enrichment arising from the same matters at issue in the Giunta Action. In April 2018, Michael Martin filed a second putative stockholder derivative action, captioned Martin v. Winemaster, et al., No. 18-CV-2386 (N.D. Ill.) (the “Martin Action”), in the same court against certain of the Company’s current and former officers and directors. In July 2018, the court consolidated the Martin Action and the Dorvit Action.

In July 2018, the plaintiffs in the consolidated Dorvit and Martin Actions filed an amended consolidated complaint (the “Second Amended Complaint”) against certain of the Company’s current and former officers and directors, who are indemnified by the Company as to their legal fees and defense costs. The Second Amended Complaint asserts claims for breach of fiduciary duty, unjust enrichment, corporate waste and failure to hold an annual stockholders’ meeting, and it seeks an unspecified amount of damages, an order compelling the Company to hold an annual stockholders’ meeting and an award of costs, including reasonable attorneys’ fees and expenses. In April 2019, the parties reached an agreement in principle to settle the litigation for approximately $1.9 million (“Settlement Amount”), half of which will be used to pay certain defense costs on behalf of the Company, and the remaining half of which the plaintiffs sought as an award of their attorneys’ fees and expenses in connection with the benefit conferred by the settlement. The settlement was approved by the court in August 2019 over two objections, including from the plaintiffs in the McClenney Action (defined below). Plaintiffs in the McClenney Action appealed the court’s order approving the settlement. On February 28, 2020, the U.S. Court of Appeals for the Seventh Circuit affirmed the district court’s approval of the settlement. Absent an extension, the plaintiffs in the McClenney Action plaintiffs have until July 27, 2020 to seek further review in the U.S. Supreme Court. The Company’s insurers made a payment of half of the Settlement Amount in September 2019 toward the fulfillment of the plaintiff’s award of attorneys’ fees and expenses, and the insurers have allocated the remaining half of the Settlement Amount toward the payment of certain defense costs consistent with the terms of the settlement. The Company had accrued for the settlement in Other accrued liabilities and for the full insurance recovery of the Settlement Amount in Prepaid expenses and other current assets as of December 31, 2018.

State Derivative Litigation

In May 2017, Lewis McClenney filed a putative stockholder derivative action in the Chancery Division of the Circuit Court of Cook County, Illinois, captioned McClenney v. Winemaster, et al., No. 2017-CH-06481 (the “McClenney Action”), against certain of the Company’s current and former officers and directors. The McClenney Action asserted claims for breach of fiduciary duty, unjust enrichment, abuse of control, gross mismanagement and corporate waste arising from the same matters at issue in the Giunta Action. On the same day that the McClenney Action was filed, Sara Rebscher also filed a putative stockholder derivative action in the same court, captioned Rebscher v. Winemaster, et al., No. 2017-CH-06517 (the “Rebscher Action”). The Rebscher Action asserts claims for breach of fiduciary duty and unjust enrichment against certain of the Company’s current and former officers and directors, arising from the same matters at issue in the Giunta Action. Additionally, the complaint in the Rebscher Action asserts a claim for professional negligence and accounting malpractice against the Company’s former auditor, RSM U.S. LLP (“RSM”). In July 2017, the court consolidated the McClenney Action and the Rebscher Action. Subsequently, the court appointed Rebscher as lead plaintiff and designated the Rebscher Action as the operative complaint. In November 2018, the court granted the Company’s motion to dismiss the consolidated case with prejudice on the grounds that it is duplicative of the Dorvit and Martin Actions. Plaintiffs moved for reconsideration of the court’s decision, which the court denied in January 2019. In February 2019, plaintiffs filed a notice of appeal from the court’s order dismissing the case. In December 2019, the Illinois Appellate Court affirmed the dismissal of the McClenney Action. Plaintiffs did not seek rehearing in the Illinois Appellate Court and did not petition for leave to appeal to the Illinois Supreme Court.

Jerome Treadwell v. the Company

In October 2018, a putative class-action complaint was filed against the Company and NOVAtime Technology, Inc. (“NOVAtime”) in the Circuit Court of Cook County, Illinois. In December 2018, NOVAtime removed the case to the U.S. District Court for the Northern District of Illinois, Eastern Division under the Class Action Fairness Act. Plaintiff has since voluntarily dismissed NOVAtime from the lawsuit without prejudice and filed an amended complaint in April 2019. The operative, amended complaint asserts violations of the Illinois Biometric Information Privacy Act (“BIPA”) in connection with employees’ use of the time clock to clock in and clock out using a finger scan and seeks statutory damages, attorneys’ fees, and injunctive and equitable relief. An aggrieved party under BIPA may recover (i) $1,000 per violation if the Company is found to have negligently violated BIPA or (ii) $5,000 per violation if the Company is found to have intentionally or recklessly violated BIPA plus reasonable attorneys’ fees. In May 2019, the Company filed its motion to dismiss the plaintiff’s amended complaint. In December 2019, the court denied the Company’s motion to dismiss. In January 2020, the Company moved for reconsideration of the court’s order denying the motion to dismiss, or in the alternative, to stay the case pending the Illinois Appellate Court’s ruling in McDonald v. Symphony Healthcare on a legal question that would be potentially dispositive in this matter. In February 2020, the court denied the Company’s motion for reconsideration, but required the parties to submit additional briefing on the Company’s motion to stay. On April 1, 2020, the Court granted the Company’s motion to stay and stayed the case pending the Illinois Appellate Court’s ruling in McDonald v. Symphony Healthcare. The Company intends to vigorously defend against this action. At this time, the Company is unable to predict the ultimate outcome of this matter or meaningfully quantify how the final resolution of this matter may impact its results of operations, financial condition or cash flows.

Don Wilkins v. the Company

In April 2017, Don Wilkins, former VP of Advanced Product Development for the Company, filed a two-count complaint alleging breach of contract by the Company and violation of the Illinois Wage Payment and Collections Act (“IWPCA”) by the Company and its former CEO, Gary Winemaster (the “Wilkins Complaint”). The Wilkins Complaint claims the Company did not have cause to terminate Mr. Wilkins’ Employment and Confidentiality Agreement (“Agreement”), executed January 6, 2012, and that the Company and Mr. Winemaster violated the IWPCA by failing to pay him accrued but unpaid vacation and earned commissions. The Wilkins Complaint seeks damages including a $2.0 million bonus entitlement in the Agreement, guaranteed annual salary to increase at 1.5 times the Consumer Price Index per year from the termination date to the end-date of the Agreement, December 31, 2020, and 20,000 shares of restricted stock granted to him in 2013 with a vesting schedule through 2020. In June 2017, the Company and Mr. Winemaster answered the complaint and asserted numerous defenses. The Company also asserted counterclaims against Wilkins including violation of the Illinois Trade Secrets Act, breach of the Agreement, breach of fiduciary duty, and spoliation. In January 2019, Mr. Wilkins voluntarily dismissed with prejudice his claims for unpaid commissions and vacation against the Company and Mr. Winemaster, subject to the parties’ confidential settlement agreement of those claims. Discovery is ongoing and no trial date has been set. In February 2020, the Company filed a motion for protective order or to stay the litigation, which the Court denied on April 7, 2020. On April 22, 2020, the parties reached an agreement in principle to settle all remaining claims for a $1.1 million payment (“Wilkins Settlement Amount”) to Mr. Wilkins. The Company will contribute $0.9 million of the Wilkins Settlement Amount which was reserved during the first quarter of 2019. The parties are working on the final settlement documents. The parties will stipulate to the dismissal of the litigation with prejudice within 7 days after payment of the Wilkins Settlement Amount.

Other Commitments

Letters of Credit

At December 31, 2019, the Company had seven outstanding letters of credit totaling $3.0 million. The letters of credit primarily serve as collateral for the Company for certain facility leases and insurance policies.

Guaranteed Minimum Commission Payment

As a result of the AGA asset acquisition discussed in Note 5. Goodwill and Other Intangibles, the Company agreed to make quarterly commission payments to the former owners with a guaranteed minimum commission payment of $1.2 million. At December 31, 2019 and 2018, $0.4 million and $1.0 million, respectively, remained outstanding related to the guaranteed minimum commission payment.

Supply Agreements

In October 2019, the Company entered into an addendum (the “Addendum”) to a supply agreement (the “Supply Agreement”), dated December 11, 2007, with a key supplier. The Addendum extends the Supply Agreement to December 31, 2023 with automatic annual extensions thereafter unless notice of termination is provided. The Addendum extends the Company’s exclusivity for the prescribed territory, but carves out of the restriction the competing engine products supplied by General Motors Company and Weichai. The Company committed to maximize sales and service opportunities on both the key supplier and Weichai engine products, recognizing their different value proposition and target markets. The Addendum also updates the minimum product purchase commitments for the period 2019 through 2023 to $40.0 million per year, subject to reductions based on market declines in oil prices and defined prescribed payments to the key supplier triggered by shortfalls in purchases made by the Company during each annual calendar period. The Company made product purchases of $47.2 million and $44.9 million in 2019 and 2018, respectively.

Given the significant decline in oil prices in early 2020, the Company is evaluating the impact of potential future purchasing volume reductions. As of December 31, 2019, no liability has been established for any possible purchasing shortfall payments.

Income Taxes

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Income Taxes

Income tax expense was as follows:



(in thousands)	For the Year Ended December 31,
	2019			2018
Current tax (benefit) expense
Federal	$	(238	)	$	198
State	91			27
Foreign	99			—
Total current tax (benefit) expense	$	(48	)	$	225

Deferred tax expense (benefit)
Federal	$	329		$	(149	)
State	128			93
Total deferred tax expense (benefit)	457			(56		)
Total tax expense	$	409		$	169

The Company received net cash refunds for income taxes of $0.3 million and $0.2 million in 2019 and 2018, respectively.

A reconciliation between the Company’s effective tax rate on income (loss) before income taxes and the statutory tax rate is as follows:



(in thousands)	For the Year Ended December 31,
	2019					2018
	Amount			Percent		Amount			Percent
Income tax expense (benefit) at federal statutory rate	$	1,818		21.0	%	$	(11,457	)	21.0	%
State income tax, net of federal benefit	618			7.1	%	(1,762		)	3.2	%
Non-deductible warrant expense	284			3.3	%	2,184			(4.0	)%
Other permanent differences	46			0.5	%	70			(0.1	)%
Research and development tax credits	(715		)	(8.3	)%	(1,058		)	1.9	%
Other tax credits	1			—	%	(934		)	1.7	%
Tax reserve reassessment	25			0.3	%	196			(0.4	)%
Change in valuation allowance	(2,696		)	(31.1	)%	12,856			(23.5	)%
Return adjustment	752			8.7	%	—			—	%
Stock-based compensation	279			3.2	%	96			(0.2	)%
Other, net	(3		)	—	%	(22		)	0.1	%
Income tax expense	$	409		4.7	%	$	169		(0.3	)%

For the year ended December 31, 2019, the Company recognized pretax income of $8.7 million, which included $1.4 million of permanently excludable loss associated with the change in the valuation and exercise of the Weichai Warrant. For the year ended December 31, 2018, the Company recognized a pretax loss of $54.6 million, which included $10.4 million of permanently excludable loss associated with the change in the valuation of the Weichai Warrant.

The Company generates R&D tax credits as a result of its R&D activities, which reduce the Company’s effective income tax rate. In general, these credits are general business credits and may be carried forward up to 20 years to be offset against future taxable income.

Significant components of deferred income tax assets and liabilities consisted of the following:



(in thousands)	As of December 31,
	2019			2018
Deferred tax assets:
Net operating loss carryforwards	$	16,389		$	19,006
Research and development credits	4,398			3,858
Other state credits	1,922			1,923
Inventory	1,718			2,203
Allowances and bad debts	1,009			840
Accrued warranty	6,344			5,732
Accrued wages and benefits	1,294			413
Other accrued expenses	1,393			5,281
Stock-based compensation	205			649
Capitalized research and development costs	486			770
163(j) disallowed interest	1,688			1,643
Intangible amortization	1,855			2,240
Contract liabilities	3,583			495
Operating lease liability	5,989			—
Other	356			847
Total deferred tax assets	48,629			45,900
Valuation allowance	(41,709		)	(44,405		)
Total deferred tax assets, net of valuation allowance	$	6,920		$	1,495

Deferred tax liabilities:
ROU operating lease asset	$	(5,652	)	$	—
Tax depreciation in excess of book depreciation on property, plant and equipment	(2,373		)	(2,142		)
Total deferred tax liabilities	$	(8,025	)	$	(2,142	)

Net deferred tax liability	$	(1,105	)	$	(647	)

The Company’s net deferred tax liability is presented as a separate line item in the Consolidated Balance Sheets.

A valuation allowance is required to be established or maintained when, based on currently available information, it is more likely than not that all or a portion of a deferred tax asset will not be realized. The guidance on accounting for income taxes provides important factors in determining whether a deferred tax asset will be realized, including whether there has been sufficient taxable income in recent years and whether sufficient income can reasonably be expected in future years in order to utilize the deferred tax asset.

The Company evaluated the need to maintain a valuation allowance for deferred tax assets based on an assessment of whether it is more likely than not that deferred tax benefits will be realized through the generation of future taxable income. Appropriate consideration is given to all available evidence, both positive and negative, in assessing the need for a valuation allowance. As a result of this evaluation, the Company concluded that the negative evidence outweighed the positive evidence and that a full valuation allowance should be maintained against its net deferred tax assets as of December 31, 2019 and 2018. The Company’s net deferred tax liability of $1.1 million and $0.6 million as of December 31, 2019 and 2018, respectively, represents the deferred tax liability related to indefinite-lived assets which cannot serve as a source of income for the realization of deferred tax assets.

As of December 31, 2019, the Company has, on a tax-effected basis, $6.3 million in R&D and state tax credit carryforwards which begin to expire in 2020. The Company has $11.4 million and $5.0 million of federal and state (tax effected, net of federal tax benefit) net operating loss carryforwards that are available to offset taxable income in the future. The federal and state net operating loss carryforwards begin to expire in 2037 and 2026, respectively. On April 23, 2019, Weichai exercised the Weichai Warrant resulting in the Company issuing 4.0 million shares of the Company’s Common Stock and Weichai becoming the owner of 51.5% of the outstanding shares of the Company’s Common Stock. The Company believes that this will constitute an “ownership change” as defined in Section 382 of the Internal Revenue Code. Consequently, all pre-ownership change tax attributes are subject to an annual Section 382 limitation. Based on the current estimated annual Section 382 limitation, the Company believes all tax attributes subject to Section 382 will be utilized prior to their expiration dates, if any.

The change in unrecognized tax benefits excluding interest and penalties were as follows:



(in thousands)	For the Year Ended December 31,
	2019			2018
Balance at beginning of year	$	1,421		$	1,307
Additions based on tax positions related to the current year	144			193
Reductions for tax positions of prior years	(135		)	(79		)
Balance at end of year	$	1,430		$	1,421

The Company recognizes interest and penalties related to unrecognized tax benefits in Income tax expense. As of December 31, 2019 and 2018, the amount accrued for interest and penalties was not material. The Company reflects the liability for unrecognized tax benefits as Other noncurrent liabilities in its Consolidated Balance Sheets. The amounts included in “reductions for tax positions of prior years” represent decreases in the unrecognized tax benefits relating to settlements reached with taxing authorities during each year shown.

As of December 31, 2019, the Company believes the liability for unrecognized tax benefits, excluding interest and penalties, could decrease by an immaterial amount in 2020 due to lapses in the statute of limitations. Due to the various jurisdictions in which the Company files tax returns, it is possible that there could be other significant changes in the amount of unrecognized tax benefits in 2020, but the amount cannot be estimated.

With few exceptions, the major jurisdictions subject to examination by the relevant tax authorities and open tax years, stated as the Company’s fiscal years, are as follows:



Jurisdiction	Open Tax Years
U.S. Federal	2014	to	2019
U.S. States	2013	to	2019
Canada	2018	to	2019

The Company is currently under federal income tax audit for tax years 2014, 2015 and 2016. The Company is currently under Illinois income tax audit for tax years 2013 and 2014.

Coronavirus Aid, Relief, and Economic Security Act

On March 27, 2020, President Trump signed into law the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”). Among the changes to the U.S. federal income tax rules, the CARES Act modified net operating loss carryback rules that were eliminated by the 2017 Tax Cuts and Jobs Act, restored 100% bonus depreciation for qualified improvement property, increased the limit on the deduction for net interest expense and accelerated the time frame for refunds of alternative minimum tax credits. The Company’s ability to carryback the net operating losses to earlier years is expected to result in a tax benefit of $0.8 million. There is no net impact to the Company’s deferred tax assets due to the full valuation allowance. The Company will continue to evaluate the effects of the CARES Act as additional legislative guidance becomes available.

Stockholders' Equity

12 Months Ended

Dec. 31, 2019

Equity [Abstract]

Stockholders' Equity

Weichai Transactions


•	2,728,752 shares of Common Stock;


•	2,385,624 shares of Series B Redeemable Convertible Preferred Stock (“Series B Convertible Preferred Stock”) that was converted into 4,771,248 shares of Common Stock in November 2017; and


•	the Weichai Warrant as discussed further below.

Weichai Warrant

Weichai Collaboration Arrangement and Related Party Transactions

Stockholders’ Equity

Common and Treasury Stock

The changes in shares of Common and Treasury Stock are as follows:



(in thousands)	Common Shares Issued	Treasury Stock Shares		Common Shares Outstanding
Balance as of December 31, 2017	19,067	634		18,433
Net shares issued for stock awards	—	(205	)	205
Balance as of December 31, 2018	19,067	429		18,638
Net shares issued for Stock awards	—	(169	)	169
Shares issued to Weichai	4,050	—		4,050
Balance as of December 31, 2019	23,117	260		22,857

Preferred Stock

Weichai Warrant

Stock-Based Compensation

12 Months Ended

Dec. 31, 2019

Share-based Payment Arrangement [Abstract]

Stock-Based Compensation

The Company has an incentive compensation plan (the “2012 Plan”), which authorizes the granting of a variety of different types of awards including, but not limited to, non-qualified stock options, incentive stock options, Stock Appreciation Rights (“SARs”), Restricted Stock Awards (“RSAs”), deferred stock and performance units to its executive officers, employees, consultants and Directors. The 2012 Plan is administered by the Compensation Committee of the Board.

Under the 2012 Plan, 830,925 shares were initially made available for awards, with 700,000 additional shares added to the 2012 Plan in 2013. Forfeited shares are added back to the pool of shares available for future awards.

As of December 31, 2019, the Company had 16,174 shares available for issuance of future awards. To date, the Company’s granted awards have generally been either RSAs or SARs.

SAR awards entitle the recipients to receive, upon exercise, a number of shares of Common Stock equal to (i) the number of shares for which the SAR is being exercised multiplied by the value of one share of Common Stock on the date of exercise (determined as provided in the SAR award agreement), less (ii) the number of shares for which the SAR is being exercised multiplied by the applicable exercise price, divided by (iii) the value of one share of Common Stock on the date of exercise (determined as provided in the SAR award agreement). The exercised SAR is to be settled only in whole shares of Common Stock, and the value of any fractional share of Common Stock is forfeited.

RSA grants represent Common Stock issued subject to forfeiture or other restrictions that will lapse upon satisfaction of specified conditions.

Both SAR awards and RSA grants are time-based awards that generally vest over a 2 to 3-year vesting schedule (except grants to members of the Board which have a 1-year vesting schedule). SAR awards generally have a term of ten years. Compensation expense for recipients of these time-based awards is recognized on a straight-line basis over the vesting period from the date of grant. The Company accounts for forfeitures as they occur rather than apply an estimated forfeiture rate. Stock-based compensation expense is primarily recorded is Selling, general and administrative expenses in the Consolidated Statements of Operations.

RSAs are valued based on the fair value of the common stock at grant date.

For all SAR award assumptions, the Company used rates on the grant date of zero-coupon government bonds with maturities over periods covering the term of the awards. The Company considered the historical volatility of its stock price over a term similar to the expected life of the awards in determining expected volatility. The expected term is the period that the awards granted are expected to remain outstanding. The Company has never declared or paid a cash dividend on its Common Stock and has no plans to pay cash dividends in the foreseeable future.

The following table represents stock-based compensation expense and the related income tax benefits:



(in thousands)	For the Year Ended December 31,
	2019		2018
Stock-based compensation expense	$	1,248	$	2,663
Income tax benefit	$	279	$	96

SAR Awards

The Company granted 9,000 and 60,000 SAR awards in 2019 and 2018, respectively. The assumptions used for determining the fair value of the SARs included the following:



	For the Year Ended December 31,
	2019			2018
Market closing price of the Common Stock	$	7.00		$	7.92
Exercise price	$	7.30		$	7.92
Risk-free interest rate	2.5		%	2.6		%
Estimated price volatility	77.8		%	78.5		%
Expected term	6.51 years			6.58 years
Dividend yield	—		%	—		%
Weighted average fair value	$	4.89		$	5.63

SAR activity consisted of the following:



Number of Shares under SARs	Shares		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (years)	Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2017	83,720		$	11.02	8.21	$	1
Granted	60,000		7.92			—
Exercised	—		—			—
Forfeited	(1,000	)	11.25			—
Expired	(4,700	)	11.25			—
Outstanding at December 31, 2018	138,020		9.66		8.05	89
Granted	9,000		7.30			—
Exercised	—		—			—
Forfeited	(7,334	)	9.81			—
Expired	(9,616	)	10.70			—
Outstanding at December 31, 2019	130,070		9.41		7.21	11

Exercisable at December 31, 2018	87,370		$	11.14	6.21	$	5
Exercisable at December 31, 2019	86,736		$	10.33	5.91	$	5

The total fair value of SARs that vested during 2019 and 2018 was $0.1 million and $0.2 million, respectively. Unrecognized compensation expense related to SARs as of December 31, 2019 and 2018 was $0.2 million. As of December 31, 2019, the weighted-average period over which the unrecognized compensation cost is expected to be recognized was approximately 1.6 years.

Restricted Stock Awards

Restricted stock activity consisted of the following:



	Shares		Weighted-Average Grant Date Fair Value
December 31, 2017	496,273		$	12.20
Granted	50,000		10.92
Forfeited	(32,547	)	25.95
Vested	(254,440	)	10.14
Balance as of December 31, 2018	259,286		$	12.25
Granted	48,000		9.72
Forfeited	(11,226	)	14.16
Vested	(230,374	)	9.83
Balance as of December 31, 2019	65,686		$	18.58

The total grant date fair value of restricted stock that vested during 2019 and 2018 was $2.3 million and $2.6 million, respectively. Unrecognized compensation expense related to RSAs as of December 31, 2019 and 2018 was $0.9 million and $1.7 million, respectively. As of December 31, 2019, the weighted-average period over which the unrecognized compensation cost is expected to be recognized was approximately 2.8 years.

Earnings (Loss) Per Share

12 Months Ended

Dec. 31, 2019

Earnings Per Share [Abstract]

Earnings (Loss) Per Share

The Company computes basic earnings (loss) per share by dividing net income (loss) by the weighted-average common shares outstanding during the year. Diluted earnings (loss) per share is calculated to give effect to all potentially dilutive common shares that were outstanding during the year. Weighted-average diluted common shares outstanding primarily reflect the additional shares that would be issued upon the assumed exercise of stock options and the assumed vesting of unvested share awards. The treasury stock method has been used to compute diluted earnings (loss) per share for 2019 and 2018.

The Company issued warrants that represent the right to purchase shares of Common Stock, SARs and RSAs, all of which have been evaluated for their potentially dilutive effect under the treasury stock method. See Note 3. Weichai Transactions for additional information on the Weichai Warrants and Note 13. Stock-Based Compensation for additional information on the SARs and the RSAs.

The computations of basic and diluted earnings (loss) per share are as follows:



(in thousands, except per share basis)	For the Year Ended December 31,
	2019		2018
Numerator:
Net income (loss) – basic and diluted	$	8,248	$	(54,726	)

Denominator:
Shares used in computing net income (loss) per share
Weighted-average common shares outstanding - basic	21,512		18,585
Effect of dilutive securities	18		—
Weighted-average common shares outstanding – diluted	21,530		18,585

Earnings (loss) per common share
Earnings (loss) per share of common stock – basic	$	0.38	$	(2.94	)
Earnings (loss) per share of common stock – diluted	$	0.38	$	(2.94	)

The aggregate number of shares excluded from the diluted earnings (loss) per share calculations because they would have been anti-dilutive were 1.4 million and 3.9 million shares in 2019 and 2018, respectively.

Related Party Transactions	12 Months Ended
Related Party Transactions	Dec. 31, 2019
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Weichai Transactions See Note 3. Weichai Transactions for information regarding the Weichai SPA and Collaboration Agreement. Transactions with Joint Ventures MAT-PSI Holdings, LLC In December 2012, the Company and MAT Holdings, Inc. (“MAT”) entered into an agreement to create MAT-PSI Holdings, LLC (“MAT-PSI”), which was intended to be a holding company of its 100% Chinese wholly-owned foreign entity, referred to as Green Power. The Company invested $0.9 million for its 50% share of MAT-PSI, which was formed to manufacture, assemble and supply natural gas, gas and alternative-fueled power systems to Chinese and Asian forklift customers. The venture established a production facility in Dalian and also sourced base engines from a local Chinese factory. As MAT-PSI was not profitable, the venture was closed in 2017; however, the Company is currently in dispute with Green Power related to the wind up of the joint venture and outstanding receivables. The dispute is currently in arbitration but is not expected to have a material impact on the Company’s financial statements. Doosan-PSI, LLC In 2015, the Company and Doosan Infracore Co., Ltd. (“Doosan”), a subsidiary of Doosan Group, entered into an agreement to form Doosan-PSI, LLC. The Company invested $1.0 million to acquire 50% of the venture, which was formed to operate in the field of developing, designing, testing, manufacturing, assembling, branding, marketing, selling, distributing and providing support for industrial gas engines and all components and materials required for assembly of the gas engines to the global power generation market outside of North America and South Korea. In the fourth quarter of 2019, Doosan and the Company agreed to wind down and dissolve the joint venture. This is expected to be completed in the second quarter of 2020. Joint Venture Operating Results The Company’s investments in joint ventures are accounted for under the equity method of accounting. The Company’s Consolidated Statement of Operations included income from these investments of $0.7 million in 2019 related to the Company’s portion of the joint ventures earnings for the year. In 2018, the earnings were immaterial. The joint venture operating results are presented in Other income, net in the Company’s Consolidated Statements of Operations. Transactions with Related Individuals Industrial Electronic Controls The Company purchased $0.4 million of products in 2018 from Industrial Electronic Controls, a supplier of custom throttles, sensors, and custom electronics. Gary S. Winemaster, former Chairman of the Board, Chief Executive Officer and President and non-executive Chief Strategy Officer divested his 50% of Industrial Electronic Controls during 2018.

Subsequent Events

12 Months Ended

Dec. 31, 2019

Subsequent Events [Abstract]

Subsequent Events

As a result of the COVID-19 pandemic, the global economy has experienced substantial turmoil including impacts from the world financial markets which have experienced a period of significant volatility and overall declines. In addition, as of the date of this 2019 Annual Report, due to unprecedented decreases in demand, an oil price war, and economic uncertainty resulting from the COVID-19 pandemic, crude oil prices declined precipitously. A significant portion of the Company’s sales and profitability is derived from the sale of products that are used within the oil and gas industry. While the Company has yet to experience significant supply chain interruptions or material cancellations of orders, the potential impact of future disruptions, continued economic uncertainty, and continued depressed crude oil prices and declining rig count levels may have a significant adverse impact on the results of future operations, financial position, and liquidity of the Company. Further, it is reasonably possible that these potential adverse impacts may result in the recognition of material impairments or other related charges.

The Company is aggressively beginning the execution of contingency actions as a result of the expected significant negative impacts of these factors. The Company is reviewing operating expenses as part of the contingency planning process, including prioritizing certain R&D investments in support of the Company’s long-term growth objectives. As of the date of this 2019 Annual Report, the Company has implemented the following temporary cost reduction measures designed to mitigate the operating and financial impacts of the COVID-19 pandemic on its business:


•	reduced the hours of operations of the Company’s production facilities;


•	reduced the work week for all office employees;


•	reduced pay for salaried employees by between 10% and 30%, depending on the employee’s position;


•	suspended the Company’s 401(k) plan match;


•	deferred spending on certain R&D programs;


•	implemented a hiring freeze;


•	restricted all non-essential travel; and


•	minimized discretionary expenses and consulting services.

On March 27, 2020, President Trump signed into law the CARES Act. The CARES Act, among other things, includes provisions relating to refundable payroll tax credits, deferment of employer side social security payments and income taxes. The income tax implications are discussed within Note 11. Income Taxes.

Summary of Significant Accounting Policies and Other Information (Policies)

12 Months Ended

Dec. 31, 2019

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Presentation and Consolidation

Reclassifications

Use of Estimates

Cash and Cash Equivalents

Research and Development

Income Taxes

Accounts Receivable and Allowance for Doubtful Accounts

Insurance Recoveries

Inventories

Property, Plant and Equipment

Repairs and maintenance costs are charged directly to expense as incurred. Major renewals or replacements that substantially extend the useful life of an asset are capitalized and depreciated.

Estimated useful lives by each type of asset category are as follows:



		Years
Buildings		Up to 39
Leasehold improvements		Lesser of (i) expected useful life of improvement or (ii) life of lease (including likely extension thereof)
Machinery and equipment		1 to 10

Intangible Assets

Impairment of Long-Lived assets

Impairment of Long-Lived Assets

Goodwill

Warranty Costs

Revenue Recognition

Recently Issued Accounting Pronouncements - Adopted and Not Yet Adopted

Recently Issued Accounting Pronouncements – Adopted

Recently Issued Accounting Pronouncements – Not Yet Adopted

Summary of Significant Accounting Policies and Other Information (Tables)

12 Months Ended

Dec. 31, 2019

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedules of Concentration of Risk, by Risk Factor

The following table presents customers individually accounting for more than 10% of the Company’s net sales:

The following table presents customers individually accounting for more than 10% of the Company’s accounts receivable:


**	Less than 10% of the total

The following table presents suppliers individually accounting for more than 10% of the Company’s purchases:

Schedule of Inventory, Current

Inventories consist of the following:



(in thousands)	As of December 31,
Inventories	2019			2018
Raw materials	$	90,677		$	90,877
Work in process	2,007			2,390
Finished goods	19,119			18,077
Total inventories	111,803			111,344
Inventory allowance	(2,964		)	(5,730		)
Inventories, net	$	108,839		$	105,614

Activity in the Company’s inventory allowance was as follows:



(in thousands)	For the Year Ended December 31,
Inventory Allowance	2019			2018
Balance at beginning of period	$	5,730		$	6,227
Charged to expense	677			2,153
Write-offs	(3,443		)	(2,650		)
Balance at end of period	$	2,964		$	5,730

Property, Plant and Equipment

Estimated useful lives by each type of asset category are as follows:



		Years
Buildings		Up to 39
Leasehold improvements		Lesser of (i) expected useful life of improvement or (ii) life of lease (including likely extension thereof)
Machinery and equipment		1 to 10

Property, plant and equipment by type were as follows:



(in thousands)	As of December 31,
Property, Plant and Equipment	2019			2018
Leasehold improvements	$	6,745		$	6,405
Machinery and equipment	41,243			38,454
Construction in progress	1,679			1,241
Total property, plant and equipment, at cost	49,667			46,100
Accumulated depreciation	(26,473		)	(21,834		)
Property, plant and equipment, net	$	23,194		$	24,266

Schedule of Other Accrued Liabilities

Other accrued liabilities consisted of the following:



(in thousands)	As of December 31,
Other Accrued Liabilities	2019		2018
Accrued product warranty	$	17,142	$	9,767
Litigation reserves ^*	5,020		16,139
Contract liabilities	26,898		4,897
Accrued compensation and benefits	6,599		4,520
Operating lease liabilities	3,789		—
Accrued interest expense	1,087		1,175
Other	5,495		9,202
Total	$	66,030	$	45,700

Schedule of Product Warranty Liability

Accrued product warranty activities are presented below:



(in thousands)	For the Year Ended December 31,
Accrued Product Warranty	2019			2018
Balance at beginning of year	$	23,102		$	12,628
Current year provision	10,349			15,840
Changes in estimates for preexisting warranties ^*	2,730			3,842
Payments made during the period	(10,680		)	(9,208		)
Balance at end of year	25,501			23,102
Less: Current portion	17,142			9,767
Noncurrent accrued product warranty	$	8,359		$	13,335

Revenue (Tables)

12 Months Ended

Dec. 31, 2019

Revenue from Contract with Customer [Abstract]

Revenue from External Customers by Geographic Areas

The following table summarizes net sales by end market:



(in thousands)	For the Year Ended December 31,
End Market	2019		2018
Energy	$	222,779	$	185,685
Industrial	180,111		201,196
Transportation	143,186		109,157
Total	$	546,076	$	496,038

The following table summarizes net sales by geographic area:



(in thousands)	For the Year Ended December 31,
Geographic Area	2019		2018
North America	$	483,302	$	436,068
Pacific Rim	39,180		42,071
Europe	16,562		13,743
Other	7,032		4,156
Total	$	546,076	$	496,038

Schedule of Contract Balances



(in thousands)	As of December 31,
	2019			2018
Short-term contract assets (included in Prepaid expenses and other current assets)	$	694		$	2,926
Short-term contract liabilities (included in Other accrued liabilities)	(26,898		)	(4,897		)
Long-term contract liabilities (included in Noncurrent contract liabilities)	(17,998		)	(14,611		)
Net contract liabilities	$	(44,202	)	$	(16,582	)

Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2019

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Estimated useful lives by each type of asset category are as follows:



		Years
Buildings		Up to 39
Leasehold improvements		Lesser of (i) expected useful life of improvement or (ii) life of lease (including likely extension thereof)
Machinery and equipment		1 to 10

Property, plant and equipment by type were as follows:



(in thousands)	As of December 31,
Property, Plant and Equipment	2019			2018
Leasehold improvements	$	6,745		$	6,405
Machinery and equipment	41,243			38,454
Construction in progress	1,679			1,241
Total property, plant and equipment, at cost	49,667			46,100
Accumulated depreciation	(26,473		)	(21,834		)
Property, plant and equipment, net	$	23,194		$	24,266

Goodwill and Other Intangibles (Tables)

12 Months Ended

Dec. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Finite-Lived Intangible Assets

Components of intangible assets are as follows:



(in thousands)	As of December 31, 2019
	Gross Carrying Value		Accumulated Amortization			Net Book Value
Customer relationships	$	34,940	$	(22,236	)	$	12,704
Developed technology	700		(605		)	95
Trade names and trademarks	1,700		(1,127		)	573
Total	$	37,340	$	(23,968	)	$	13,372



(in thousands)	As of December 31, 2018
	Gross Carrying Value		Accumulated Amortization			Net Book Value
Customer relationships	$	34,940	$	(18,816	)	$	16,124
Developed technology	700		(537		)	163
Trade names and trademarks	1,700		(977		)	723
Total	$	37,340	$	(20,330	)	$	17,010

Schedule of Future Amortization Expense

Estimated future amortization expense for intangible assets as of December 31, 2019 is as follows:



(in thousands)
Year Ending December 31,	Estimated Amortization
2020	$	3,053
2021	2,535
2022	2,124
2023	1,746
2024	1,459
2025 and beyond	2,455
Total	$	13,372

Debt (Tables)

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Schedule of Debt

The Company’s outstanding debt consisted of the following:



(in thousands)	As of December 31,
	2019			2018
Short-term financing:
Wells Fargo revolving credit facility	$	39,527		$	54,613

Long-term debt:
Unsecured senior notes	$	55,000		$	55,000
Finance leases and other debt	1,087			456
Unamortized debt issuance costs ^*	(235		)	(288		)
Total long-term debt and finance leases	55,852			55,168
Less: Current maturities of long-term debt and finance leases	195			80
Long-term debt	$	55,657		$	55,088


*	Unamortized financing costs and deferred fees on the Wells Fargo Revolving Credit Facility are not presented in the above table as they are classified in Prepaid expenses and other current assets on the Consolidated Balance Sheets. Debt issuance costs incurred, including gross waiver fees (primarily paid to the lenders), were $0.3 million and $1.0 million in 2019 and 2018, respectively.

ignificant amendments to the Unsecured Senior Notes since January 1, 2018 are included in the table below:



Amendment Date and Title	Reason for Amendment	Significant Changes/Notes Related to Amendment to the Unsecured Senior Notes
April 19, 2018. Fourth Supplemental Indenture	To amend certain covenants and waive certain events of default	• Extended the maturity date to January 1, 2020 • Waived defaults with respect to the failure to file with the Trustee and the SEC for 2015 through 2019 • Increased the interest rate from 6.50% to 8.50% per annum effective October 1, 2018. The interest rate decreased to 7.50% per annum upon filing the 2017 Form 10-K with the SEC • the Company paid a consent fee of $0.3 million.
October 30, 2019. Fifth Supplemental Indenture	To extend the maturity date	• Extended maturity date to June 30, 2020 • The Company paid a fee of $0.3 million

Schedule of Line of Credit Facilities

Information regarding amounts borrowed under the Wells Fargo Credit Agreement includes the following:



(in thousands, except interest rate)	Year ended December 31,
Description	2019			2018
Average borrowings under Wells Fargo Revolving Credit Facility	$	48,235		$	47,031
Average Interest Cost on Wells Fargo Revolving Credit Facility	6.30		%	6.51		%



(in thousands, except interest rate)	As of December 31,
Description	2019			2018
Accrued and unpaid interest	$	400		$	174
LIBOR loan interest rate	5.00		%	5.97		%
Wells Fargo Prime Rate (Base Rate) loan interest rate	6.25		%	7.25		%

Significant changes to the Wells Fargo Credit Agreement since January 1, 2018 are summarized in the table below:



Amendment Date and Title	Reason for Amendment	Significant Changes/Notes Regarding Amendment to the Wells Fargo Credit Agreement
March 29, 2018. Sixth Amendment and Waiver to the June 28, 2016 Agreement	To consider implications of various events of default	• Increased the maximum borrowing under the revolving credit facility to $75.0 million from $65.0 million • Modified the reserve against the maximum borrowing under the revolving credit facility to the greater of $6.5 million and 10% of borrowing base, but no more than $7.5 million on or prior to September 30, 2018 and thereafter equal to $9.0 million • Extended the maturity date of the facility to the earlier of March 31, 2021 or 60 days prior to the final maturity of the Unsecured Senior Notes, which were extended to January 1, 2020, resulting in a maturity date of November 2, 2019 on the Wells Fargo revolving credit facility • The revolving credit facility will continue to bear interest at a per annum rate equal to 100 basis points (1%) above the per annum rate otherwise applicable under the credit agreement until the Company is current with its SEC filings • The Company paid an amendment fee of $0.8 million.
May 16, 2019. Waiver to the June 28, 2016 Agreement	To consider implications of various events of default	• Waived any defaults that would arise from the failure to timely deliver annual audited financial statements for the fiscal year ended December 31, 2018 and the associated compliance certificate and the information required with it; provided that the financial statements and compliance certificate were delivered on or before December 31, 2019.

Schedule of Maturities of Long-term Debt



(in thousands)
Year Ending December 31,	Maturities of Long-Term Debt
2020	$	107
2021	55,107
2022	101
2023	91
2024	91
Total	$	55,497

Leases (Tables)

12 Months Ended

Dec. 31, 2019

Leases [Abstract]

Components of Lease Expense and Cash Flow Information

The following table presents supplemental cash flow information related to leases:



(in thousands)	For the Year Ended December 31,
	2019
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows paid for operating leases	$	5,181
Operating cash flows paid for interest portion of finance leases	49
Financing cash flows paid for principal portion of finance leases	152
Right-of-use assets obtained in exchange for lease obligations
Operating leases	280
Finance leases	536

The following table summarizes the components of lease expense:



(in thousands)	For the Year Ended December 31,
	2019
Operating lease cost	$	5,472
Finance lease cost:
Amortization of ROU asset	170
Interest expense	49
Short-term lease cost	492
Variable lease cost	1,675
Total lease cost	$	7,858

Supplemental Balance Sheet Information

The following table presents supplemental balance sheet information related to leases as of December 31, 2019:



(in thousands)	Operating Leases		Finance Leases
ROU assets, net ¹	$	20,677	$	777

Lease liabilities, current ²	3,789		195
Lease liabilities, non-current ³	17,679		617
Total lease liabilities	$	21,468	$	812

1. Included in Other noncurrent assets for operating leases and Property, plant and equipment, net for finance leases on the Consolidated Balance Sheet.

2. Included in Other accrued liabilities for operating leases and Current maturities of long-term debt for finance leases on the Consolidated Balance Sheet.


3.	Included in Other noncurrent liabilities for operating leases and Long-term debt, net of current maturities for finance leases on the Consolidated Balance Sheet.

Maturity Analysis of Operating Lease Liabilities

The following table presents maturity analysis of lease liabilities as of December 31, 2019:



(in thousands)
Year Ending December 31,	Operating Leases		Finance Leases
2020	$	5,210	$	243
2021	4,827		243
2022	4,668		175
2023	3,247		101
2024	1,813		82
Thereafter	7,389		96
Total undiscounted lease payments	27,154		940
Less: imputed interest	5,686		128
Total lease liabilities	$	21,468	$	812

Maturity Analysis of Financing Lease Liabilities

The following table presents maturity analysis of lease liabilities as of December 31, 2019:



(in thousands)
Year Ending December 31,	Operating Leases		Finance Leases
2020	$	5,210	$	243
2021	4,827		243
2022	4,668		175
2023	3,247		101
2024	1,813		82
Thereafter	7,389		96
Total undiscounted lease payments	27,154		940
Less: imputed interest	5,686		128
Total lease liabilities	$	21,468	$	812

Future Minimum Lease Payments Under Operating and Capital Leases

The future minimum lease payments due under operating and capital leases in effect, as amended and extended, as of December 31, 2018, under the previous lease guidance, were as follows:



(in thousands)	Operating		Capital
2019	$	5,071	$	80
2020	5,175		63
2021	4,724		67
2022	4,681		50
2023	3,104		13
2024 and beyond	3,694		—
Total	$	26,449	$	273

Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Schedule of Fair Value Measurements at Reporting Date



(in thousands)	As of December 31, 2019
	Carrying Value		Fair Value
	Carrying Value		Level 1		Level 2		Level 3
Wells Fargo Credit Agreement	$	39,527	$	—	$	39,527	$	—
Unsecured Senior Notes	54,765		—		—		54,600



(in thousands)	As of December 31, 2018
	Carrying Value		Fair Value
	Carrying Value		Level 1		Level 2		Level 3
Wells Fargo Credit Agreement	$	54,613	$	—	$	54,613	$	—
Unsecured Senior Notes	54,712		—		—		52,700



(in thousands)	As of December 31, 2018
	Carrying Value		Fair Value
	Carrying Value		Level 1		Level 2		Level 3
Warrant liability	$	35,100	$	—	$	—	$	35,100

Summary of Change in the Estimated Fair Value of Private Placement Warrants

The following table summarizes changes in the estimated fair value of the Company’s warrant liability:



(in thousands)	As of December 31,
	2019			2018
Balance at beginning of year	$	35,100		$	24,700
Change in value of warrants ^*	1,352			10,400
Settlement of warrants	(36,452		)	—
Balance at end of year	$	—		$	35,100


*	The change in value of the warrant liability for each year is presented in Loss from change in value and exercise of warrants in the Company’s Consolidated Statements of Operations. The change in value for the year ended December 31, 2019 includes the impact of Weichai exercising the warrant in April 2019.

Schedule of Inputs of the Black-Scholes Option Pricing Model

The inputs of the Black-Scholes option pricing model were as follows:



Assumptions	As of December 31,
Assumptions	2018
Market value of the Common Stock	$	9.25
Exercise price	varies
Risk-free interest rate	2.6		%
Estimated price volatility	55.0		%
Contractual term	0.5 years

- Definition

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Stock-Based Compensation Expense

Income tax expense was as follows:



(in thousands)	For the Year Ended December 31,
	2019			2018
Current tax (benefit) expense
Federal	$	(238	)	$	198
State	91			27
Foreign	99			—
Total current tax (benefit) expense	$	(48	)	$	225

Deferred tax expense (benefit)
Federal	$	329		$	(149	)
State	128			93
Total deferred tax expense (benefit)	457			(56		)
Total tax expense	$	409		$	169

The following table represents stock-based compensation expense and the related income tax benefits:



(in thousands)	For the Year Ended December 31,
	2019		2018
Stock-based compensation expense	$	1,248	$	2,663
Income tax benefit	$	279	$	96

Reconciliation of Effective Tax Rate to the Statutory Rate

A reconciliation between the Company’s effective tax rate on income (loss) before income taxes and the statutory tax rate is as follows:



(in thousands)	For the Year Ended December 31,
	2019					2018
	Amount			Percent		Amount			Percent
Income tax expense (benefit) at federal statutory rate	$	1,818		21.0	%	$	(11,457	)	21.0	%
State income tax, net of federal benefit	618			7.1	%	(1,762		)	3.2	%
Non-deductible warrant expense	284			3.3	%	2,184			(4.0	)%
Other permanent differences	46			0.5	%	70			(0.1	)%
Research and development tax credits	(715		)	(8.3	)%	(1,058		)	1.9	%
Other tax credits	1			—	%	(934		)	1.7	%
Tax reserve reassessment	25			0.3	%	196			(0.4	)%
Change in valuation allowance	(2,696		)	(31.1	)%	12,856			(23.5	)%
Return adjustment	752			8.7	%	—			—	%
Stock-based compensation	279			3.2	%	96			(0.2	)%
Other, net	(3		)	—	%	(22		)	0.1	%
Income tax expense	$	409		4.7	%	$	169		(0.3	)%

Schedule of Significant Components of the Deferred Income Tax Assets and Liabilities

Significant components of deferred income tax assets and liabilities consisted of the following:



(in thousands)	As of December 31,
	2019			2018
Deferred tax assets:
Net operating loss carryforwards	$	16,389		$	19,006
Research and development credits	4,398			3,858
Other state credits	1,922			1,923
Inventory	1,718			2,203
Allowances and bad debts	1,009			840
Accrued warranty	6,344			5,732
Accrued wages and benefits	1,294			413
Other accrued expenses	1,393			5,281
Stock-based compensation	205			649
Capitalized research and development costs	486			770
163(j) disallowed interest	1,688			1,643
Intangible amortization	1,855			2,240
Contract liabilities	3,583			495
Operating lease liability	5,989			—
Other	356			847
Total deferred tax assets	48,629			45,900
Valuation allowance	(41,709		)	(44,405		)
Total deferred tax assets, net of valuation allowance	$	6,920		$	1,495

Deferred tax liabilities:
ROU operating lease asset	$	(5,652	)	$	—
Tax depreciation in excess of book depreciation on property, plant and equipment	(2,373		)	(2,142		)
Total deferred tax liabilities	$	(8,025	)	$	(2,142	)

Net deferred tax liability	$	(1,105	)	$	(647	)

Schedule of the Change in Unrecognized Tax Benefits

The change in unrecognized tax benefits excluding interest and penalties were as follows:



(in thousands)	For the Year Ended December 31,
	2019			2018
Balance at beginning of year	$	1,421		$	1,307
Additions based on tax positions related to the current year	144			193
Reductions for tax positions of prior years	(135		)	(79		)
Balance at end of year	$	1,430		$	1,421

Summary of Income Tax Examinations

With few exceptions, the major jurisdictions subject to examination by the relevant tax authorities and open tax years, stated as the Company’s fiscal years, are as follows:



Jurisdiction	Open Tax Years
U.S. Federal	2014	to	2019
U.S. States	2013	to	2019
Canada	2018	to	2019

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2019

Equity [Abstract]

Schedule of Common Stock Outstanding Roll Forward

The changes in shares of Common and Treasury Stock are as follows:



(in thousands)	Common Shares Issued	Treasury Stock Shares		Common Shares Outstanding
Balance as of December 31, 2017	19,067	634		18,433
Net shares issued for stock awards	—	(205	)	205
Balance as of December 31, 2018	19,067	429		18,638
Net shares issued for Stock awards	—	(169	)	169
Shares issued to Weichai	4,050	—		4,050
Balance as of December 31, 2019	23,117	260		22,857

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Share-based Payment Arrangement [Abstract]

Stock-Based Compensation Expense

Income tax expense was as follows:



(in thousands)	For the Year Ended December 31,
	2019			2018
Current tax (benefit) expense
Federal	$	(238	)	$	198
State	91			27
Foreign	99			—
Total current tax (benefit) expense	$	(48	)	$	225

Deferred tax expense (benefit)
Federal	$	329		$	(149	)
State	128			93
Total deferred tax expense (benefit)	457			(56		)
Total tax expense	$	409		$	169

The following table represents stock-based compensation expense and the related income tax benefits:



(in thousands)	For the Year Ended December 31,
	2019		2018
Stock-based compensation expense	$	1,248	$	2,663
Income tax benefit	$	279	$	96

Schedule of Fair Value Assumptions

The assumptions used for determining the fair value of the SARs included the following:



	For the Year Ended December 31,
	2019			2018
Market closing price of the Common Stock	$	7.00		$	7.92
Exercise price	$	7.30		$	7.92
Risk-free interest rate	2.5		%	2.6		%
Estimated price volatility	77.8		%	78.5		%
Expected term	6.51 years			6.58 years
Dividend yield	—		%	—		%
Weighted average fair value	$	4.89		$	5.63

Schedule of SAR Activity

SAR activity consisted of the following:



Number of Shares under SARs	Shares		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (years)	Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2017	83,720		$	11.02	8.21	$	1
Granted	60,000		7.92			—
Exercised	—		—			—
Forfeited	(1,000	)	11.25			—
Expired	(4,700	)	11.25			—
Outstanding at December 31, 2018	138,020		9.66		8.05	89
Granted	9,000		7.30			—
Exercised	—		—			—
Forfeited	(7,334	)	9.81			—
Expired	(9,616	)	10.70			—
Outstanding at December 31, 2019	130,070		9.41		7.21	11

Exercisable at December 31, 2018	87,370		$	11.14	6.21	$	5
Exercisable at December 31, 2019	86,736		$	10.33	5.91	$	5

Schedule of Restricted Stock Activity

Restricted stock activity consisted of the following:



	Shares		Weighted-Average Grant Date Fair Value
December 31, 2017	496,273		$	12.20
Granted	50,000		10.92
Forfeited	(32,547	)	25.95
Vested	(254,440	)	10.14
Balance as of December 31, 2018	259,286		$	12.25
Granted	48,000		9.72
Forfeited	(11,226	)	14.16
Vested	(230,374	)	9.83
Balance as of December 31, 2019	65,686		$	18.58

Earnings (Loss) Per Share (Tables)

12 Months Ended

Dec. 31, 2019

Earnings Per Share [Abstract]

Schedule of Basic and Diluted Earnings (Loss) Per Share

The computations of basic and diluted earnings (loss) per share are as follows:



(in thousands, except per share basis)	For the Year Ended December 31,
	2019		2018
Numerator:
Net income (loss) – basic and diluted	$	8,248	$	(54,726	)

Denominator:
Shares used in computing net income (loss) per share
Weighted-average common shares outstanding - basic	21,512		18,585
Effect of dilutive securities	18		—
Weighted-average common shares outstanding – diluted	21,530		18,585

Earnings (loss) per common share
Earnings (loss) per share of common stock – basic	$	0.38	$	(2.94	)
Earnings (loss) per share of common stock – diluted	$	0.38	$	(2.94	)

Summary of Significant Accounting Policies and Other Information - Narrative (Details)		1 Months Ended	3 Months Ended		12 Months Ended
	Apr. 02, 2020 USD ($)	Mar. 31, 2017 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) board_member reporting_unit segment	Dec. 31, 2018 USD ($)
Concentration Risk [Line Items]
Number of board members \| board_member					3
Number of operating segments \| segment					1
Research and development and engineering expenses					$ 23,300,000	$ 26,800,000
Insurance recoveries					3,600,000	16,000,000
Asset impairment charges				$ 2,234,000	$ 1,000	2,234,000
Number of reporting units \| reporting_unit					2
Impairment losses					$ 0	0
Changes in estimates for preexisting warranties			$ 2,700,000		$ 2,730,000	$ 3,842,000
Minimum
Concentration Risk [Line Items]
Amortization period					3 years
Maximum
Concentration Risk [Line Items]
Amortization period					15 years
Revolving Credit Facility
Concentration Risk [Line Items]
Maturity period prior to the final maturity					60 days
Share Purchase Agreement, Weichai Transaction
Concentration Risk [Line Items]
Consideration received on transaction		$ 60,000,000
Subsequent Event \| Standard Chartered Bank Credit Agreement \| Revolving Credit Facility
Concentration Risk [Line Items]
Maximum borrowing capacity	$ 130,000,000
Maturity period prior to the final maturity	60 days
Extension fee	0.25%

Summary of Significant Accounting Policies and Other Information - Schedules of Concentration of Risk, by Risk Factor (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Purchases \| Supplier Concentration Risk \| Supplier A
Concentration Risk [Line Items]
Concentration risk, percentage	25.00%	19.00%
Purchases \| Supplier Concentration Risk \| Supplier B
Concentration Risk [Line Items]
Concentration risk, percentage	13.00%	13.00%
Customer A \| Net sales \| Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	17.00%	11.00%
Customer A \| Accounts Receivable \| Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	49.00%	25.00%
Customer B \| Net sales \| Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	13.00%	15.00%
Customer B \| Accounts Receivable \| Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage		15.00%

Summary of Significant Accounting Policies and Other Information - Schedule of Inventory, Current (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Inventories
Raw materials	$ 90,677	$ 90,877
Work in process	2,007	2,390
Finished goods	19,119	18,077
Total inventories	111,803	111,344
Inventory allowance	(2,964)	(5,730)
Inventories, net	108,839	105,614
Inventory Allowance
Balance at beginning of period	5,730	6,227
Charged to expense	677	2,153
Write-offs	(3,443)	(2,650)
Balance at end of period	$ 2,964	$ 5,730

Summary of Significant Accounting Policies and Other Information - Property, Plant and Equipment (Details)	12 Months Ended
	Dec. 31, 2019
Buildings \| Maximum
Property, Plant and Equipment [Line Items]
Useful life	39 years
Machinery and equipment \| Maximum
Property, Plant and Equipment [Line Items]
Useful life	10 years
Machinery and equipment \| Minimum
Property, Plant and Equipment [Line Items]
Useful life	1 year

Summary of Significant Accounting Policies and Other Information - Schedule of Other Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued product warranty	$ 17,142	$ 9,767
Litigation reserves	5,020	16,139
Contract liabilities	26,898	4,897
Accrued compensation and benefits	6,599	4,520
Operating lease liabilities	3,789
Accrued interest expense	1,087	1,175
Other	5,495	9,202
Total	66,030	45,700
Litigation reserves	$ 1,900	$ 14,000

Summary of Significant Accounting Policies and Other Information - Schedule of Accrued Product Warranty (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Accrued Product Warranty
Balance at beginning of year	$ 23,102	$ 23,102	$ 12,628
Current year provision		10,349	15,840
Changes in estimates for preexisting warranties	$ 2,700	2,730	3,842
Payments made during the period		(10,680)	(9,208)
Balance at end of year		25,501	23,102
Less: Current portion		17,142	9,767
Noncurrent accrued product warranty		$ 8,359	$ 13,335
Diluted share (in dollars per share)	$ 0.13

Revenue - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Revenue - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue recognized at a point in time	$ 489.0	$ 449.8
Revenue recognized over time	57.1	$ 46.2
Revenue recognized upon satisfaction of performance obligations	6.7
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 41.8
Revenue, remaining performance obligation, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 23.8
Revenue, remaining performance obligation, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 15.6
Revenue, remaining performance obligation, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 0.7
Revenue, remaining performance obligation, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 0.7
Revenue, remaining performance obligation, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 1.0
Revenue, remaining performance obligation, period	1 year

Revenue - Revenue from External Customers by Geographic Areas (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Net sales	$ 546,076	$ 496,038
North America
Disaggregation of Revenue [Line Items]
Net sales	483,302	436,068
Pacific Rim
Disaggregation of Revenue [Line Items]
Net sales	39,180	42,071
Europe
Disaggregation of Revenue [Line Items]
Net sales	16,562	13,743
Other
Disaggregation of Revenue [Line Items]
Net sales	7,032	4,156
Energy
Disaggregation of Revenue [Line Items]
Net sales	222,779	185,685
Industrial
Disaggregation of Revenue [Line Items]
Net sales	180,111	201,196
Transportation
Disaggregation of Revenue [Line Items]
Net sales	$ 143,186	$ 109,157

Revenue - Schedule of Contract Balances (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Short-term contract assets (included in Prepaid expenses and other current assets)	$ 694	$ 2,926
Short-term contract liabilities (included in Other accrued liabilities)	(26,898)	(4,897)
Long-term contract liabilities (included in Noncurrent contract liabilities)	(17,998)	(14,611)
Net contract liabilities	$ (44,202)	$ (16,582)

Weichai Transactions (Details) - Share Purchase Agreement, Weichai Transaction - USD ($)	1 Months Ended		12 Months Ended
	Nov. 30, 2017	Mar. 31, 2017	Dec. 31, 2019
Subsidiary, Sale of Stock [Line Items]
Consideration received on transaction		$ 60,000,000
Common Stock
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction (in shares)		2,728,752	4,050,000
Redeemable Convertible Series B Preferred Stock
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction (in shares)		2,385,624
Issuance of redeemable convertible Series B Preferred Stock, net of fees (in shares)	4,771,248

Weichai Transactions - Weichai Warrant (Details) - USD ($) $ in Thousands			1 Months Ended	12 Months Ended
	Apr. 23, 2019	Oct. 01, 2018	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018
Class of Warrant or Right [Line Items]
Exercise proceeds for the warrants				$ 1,616	$ 0
Share Purchase Agreement, Weichai Transaction
Class of Warrant or Right [Line Items]
Exercisable (term)			90 days
Volume weighted average share price percentage		50.00%
Trading period		20 days
Aggregate amount		$ 15,000
Expense as a result of the exercise	$ 1,400
Share Purchase Agreement, Second Amended And Restated Warrant \| Series B Convertible Preferred Stock
Class of Warrant or Right [Line Items]
Exercise of private placement warrants (in shares)	4,049,759
Percent ownership of outstanding common stock	51.50%
Exercise proceeds for the warrants	$ 1,600

Weichai Transactions - Weichai Collaboration Arrangement (Details) - USD ($) $ in Millions		12 Months Ended
	Mar. 20, 2017	Dec. 31, 2019	Dec. 31, 2018
Equity [Abstract]
Term of collaborative arrangement	3 years
Purchased inventory		$ 4.4	$ 3.5
Outstanding payables		$ 5.9	$ 3.7

Property, Plant and Equipment - Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Apr. 30, 2018
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, at cost	$ 49,667	$ 46,100
Accumulated depreciation	(26,473)	(21,834)
Property, plant and equipment, net	23,194	24,266
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, at cost	6,745	6,405
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, at cost	41,243	38,454	$ 6,900
Construction in progress
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, at cost	$ 1,679	$ 1,241

Property, Plant and Equipment - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended
	Apr. 30, 2018	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property, plant and equipment		$ 49,667	$ 46,100
Asset retirement obligation	$ 1,300
Machinery and equipment
Property, Plant and Equipment [Line Items]
Purchase price	5,600
Property, plant and equipment	$ 6,900	$ 41,243	$ 38,454

Goodwill and Other Intangibles - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended	12 Months Ended
	Mar. 31, 2018	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Goodwill			$ 29,835	$ 29,835	$ 29,835
Accumulated impairment losses			11,600	11,600	11,600
Asset impairment charges			$ 2,234	1	2,234
Asset Purchase Agreement - Alternative Fuel Supply Technology
Finite-Lived Intangible Assets [Line Items]
Guaranteed payment	$ 1,200	$ 1,200		$ 400	1,000
Additional payment for future sales milestones	3,300
Asset Purchase Agreement - Alternative Fuel Supply Technology \| Intellectual Property
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired	1,500				$ 1,000	$ 500
Asset Purchase Agreement - Alternative Fuel Supply Technology \| Developed technology
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired	$ 2,700
Useful life	3 years

Goodwill and Other Intangibles - Schedule of Finite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 37,340	$ 37,340
Accumulated Amortization	(23,968)	(20,330)
Net Book Value	13,372	17,010
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	34,940	34,940
Accumulated Amortization	(22,236)	(18,816)
Net Book Value	12,704	16,124
Developed technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	700	700
Accumulated Amortization	(605)	(537)
Net Book Value	95	163
Trade names and trademarks
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	1,700	1,700
Accumulated Amortization	(1,127)	(977)
Net Book Value	$ 573	$ 723

Goodwill and Other Intangibles - Schedule of Future Amortization Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Year Ending December 31,
2020	$ 3,053
2021	2,535
2022	2,124
2023	1,746
2024	1,459
2025 and beyond	2,455
Net Book Value	$ 13,372	$ 17,010

Debt - Schedule of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Long Term Debt And Short Term Debt Instruments [Line Items]
Long-term debt	$ 55,497
Finance leases and other debt	1,087	$ 456
Unamortized debt issuance costs	(235)	(288)
Total long-term debt and finance leases	55,852	55,168
Less: Current maturities of long-term debt and finance leases	195	80
Long-term debt	55,657	55,088
Debt issuance costs	300	1,000
Unsecured senior notes
Schedule Of Long Term Debt And Short Term Debt Instruments [Line Items]
Long-term debt	55,000	55,000
Wells Fargo revolving credit facility
Schedule Of Long Term Debt And Short Term Debt Instruments [Line Items]
Short-term financing	$ 39,527	$ 54,613

Debt - Debt Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Debt - Debt Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
Interest paid	$ 6.9	$ 6.1

Debt - Wells Fargo Credit Agreement - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Mar. 29, 2018	Mar. 31, 2017
Line of Credit Facility [Line Items]
Debt issuance costs	$ 300,000	$ 1,000,000
Wells Fargo Credit Agreement
Line of Credit Facility [Line Items]
Lender fees			$ 800,000
Revolving Credit Facility \| Wells Fargo Credit Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity	75,000,000		$ 75,000,000	$ 65,000,000
Reserve against borrowing base availability	$ 9,000,000
Unused line fee percentage	0.25%
Available revolving line of credit balance	$ 14,900,000	8,900,000
Debt issuance costs	$ 0
Lender fees		$ 800,000
Revolving Credit Facility \| Wells Fargo Credit Agreement \| Minimum \| Prime Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.25%
Revolving Credit Facility \| Wells Fargo Credit Agreement \| Minimum \| LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate	2.75%
Revolving Credit Facility \| Wells Fargo Credit Agreement \| Maximum \| Prime Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.75%
Revolving Credit Facility \| Wells Fargo Credit Agreement \| Maximum \| LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate	3.25%
Revolving Credit Facility
Line of Credit Facility [Line Items]
Maturity period prior to the final maturity	60 days
Debt instrument, interest rate	1.00%

Debt - Schedule of Amounts Borrowed Under Wells Fargo Revolving Credit Agreement (Details) - Wells Fargo Credit Agreement - Wells Fargo revolving credit facility - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Line of Credit Facility [Line Items]
Average borrowings under Wells Fargo Revolving Credit Facility	$ 48,235	$ 47,031
Average Interest Cost on Wells Fargo Revolving Credit Facility	6.30%	6.51%
Accrued and unpaid interest	$ 400	$ 174
LIBOR
Line of Credit Facility [Line Items]
LIBOR loan interest rate	5.00%	5.97%
Prime Rate
Line of Credit Facility [Line Items]
Wells Fargo Prime Rate (Base Rate) loan interest rate	6.25%	7.25%

Debt - Wells Fargo Credit Agreement - Amendments (Details) - Wells Fargo Credit Agreement - USD ($)	Mar. 29, 2018	Dec. 31, 2018	Oct. 01, 2018
Line of Credit Facility [Line Items]
Lender fees	$ 800,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Commitment fee percentage	1.00%
Maturity, period prior to senior notes maturity	60 days
Line of credit facility, increase limit			$ 9,000,000.0
Percentage of borrowing base	10.00%
Lender fees		$ 800,000
Revolving Credit Facility \| Minimum
Line of Credit Facility [Line Items]
Line of credit facility, increase limit	$ 6,500,000.0
Revolving Credit Facility \| Maximum
Line of Credit Facility [Line Items]
Line of credit facility, increase limit	$ 7,500,000.0

Debt - Unsecured Senior Notes - Narrative (Details) - USD ($)	1 Months Ended	12 Months Ended
	Apr. 30, 2015	Dec. 31, 2019	Oct. 30, 2019	May 31, 2019	Dec. 31, 2018	Apr. 19, 2018	Apr. 01, 2016
Debt Instrument [Line Items]
Debt financing costs		$ 300,000			$ 1,000,000
Unsecured senior notes
Debt Instrument [Line Items]
Debt instrument, interest rate							6.50%
Consent fee		$ 300,000	$ 300,000		300,000	$ 300,000
Unsecured senior notes \| 5.50% Senior Notes
Debt Instrument [Line Items]
Debt instrument, face amount	$ 55,000,000
Debt instrument, interest rate	5.50%	8.50%
Proceeds from issuance of long-term debt	$ 53,500,000
Debt financing costs	$ 1,500,000
Accrued unpaid interest		$ 700,000			$ 800,000
Unsecured senior notes \| 5.50% Senior Notes \| Before May 1, 2016
Debt Instrument [Line Items]
Redemption price, percentage		101.00%
Revolving Credit Facility and Senior Notes
Debt Instrument [Line Items]
Debt instrument, interest rate				7.50%

Debt - Senior Notes - Amendments (Details) - Unsecured senior notes - USD ($) $ in Millions	Dec. 31, 2019	Oct. 30, 2019	Dec. 31, 2018	Apr. 19, 2018	Apr. 01, 2016
Debt Instrument [Line Items]
Debt instrument, interest rate					6.50%
Interest rate if Form 10-K is filed on or before September 30, 2018				7.50%
Interest rate if Form 10-K has not been filed on or before September 30, 2018				8.50%
Interest rate subsequent to Form 10-K filing				7.50%
Consent fee	$ 0.3	$ 0.3	$ 0.3	$ 0.3

Debt - Credit Agreement - Narrative (Details) - USD ($)	Apr. 02, 2020	Dec. 31, 2019	Dec. 31, 2018	Mar. 29, 2018	Mar. 31, 2017	Apr. 30, 2015
Debt Instrument [Line Items]
Debt issuance costs		$ 300,000	$ 1,000,000
Unsecured senior notes \| 5.50% Senior Notes
Debt Instrument [Line Items]
Debt issuance costs						$ 1,500,000
Wells Fargo revolving credit facility \| Wells Fargo Credit Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity		75,000,000		$ 75,000,000	$ 65,000,000
Debt issuance costs		$ 0
Subsequent Event \| Unsecured senior notes \| 5.50% Senior Notes
Debt Instrument [Line Items]
Redemption and discharge of debt	$ 55,000,000
Subsequent Event \| Wells Fargo revolving credit facility \| Standard Chartered Bank Credit Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity	130,000,000
Borrowing amount	95,000,000
Loss on extinguishment of debt	100,000
Debt issuance costs	$ 2,000,000
Maturity period prior to the final maturity	60 days
Extension fee	0.25%
Basis spread on variable rate	0.25%
Subsequent Event \| Wells Fargo revolving credit facility \| Standard Chartered Bank Credit Agreement \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	2.00%
Subsequent Event \| Wells Fargo revolving credit facility \| Wells Fargo Credit Agreement
Debt Instrument [Line Items]
Repayment of debt	$ 16,800,000

Debt - Schedule of Maturities of Long-Term Debt (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Debt Disclosure [Abstract]
2020	$ 107
2021	55,107
2022	101
2023	91
2024	91
Total	$ 55,497

Leases - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Leases - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
ROU assets, net	$ 20,677
Operating lease liabilities	21,468
Lease expense	$ 7,858
Rent expense related to operating leases		$ 5,100
Weighted-average remaining lease term, operating lease	6 years 8 months 19 days
Weighted-average remaining lease term, financing leases	4 years 6 months 14 days
Weighted-average discount rate for operating leases	7.20%
Weighted-average discount rate for financing leases	6.80%
ASC 842
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
ROU assets, net			$ 24,600
Operating lease liabilities			$ 25,100
Cost of Sales
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lease expense	$ 6,900
Research, Development and Engineering
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lease expense	700
Selling, General and Administrative Expenses
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lease expense	300
Interest Expense
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lease expense	$ 100

Leases - Components of Lease Expense (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Leases [Abstract]
Operating lease cost	$ 5,472
Finance lease cost:
Amortization of ROU asset	170
Interest expense	49
Short-term lease cost	492
Variable lease cost	1,675
Total lease cost	$ 7,858

Leases - Supplemental Cash Flow Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows paid for operating leases	$ 5,181
Operating cash flows paid for interest portion of finance leases	49
Financing cash flows paid for principal portion of finance leases	152
Right-of-use assets obtained in exchange for lease obligations
Operating leases	280
Finance leases	$ 536

Leases - Supplemental Balance Sheet Information (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Operating Leases
ROU assets, net	$ 20,677
Lease liabilities, current	3,789
Lease liabilities, non-current	17,679
Total lease liabilities	21,468
Finance Leases
ROU assets, net	777
Lease liabilities, current	195
Lease liabilities, non-current	617
Total lease liabilities	$ 812
Operating ROU assets, net, statement of financial position [Extensible List]	us-gaap:OtherAssetsNoncurrent
Financing ROU assets, net, statement of financial position [Extensible List]	us-gaap:PropertyPlantAndEquipmentNet
Operating lease liabilities, current, statement of financial position [Extensible List]	us-gaap:OtherAccruedLiabilitiesCurrent
Financing lease liabilities, current, statement of financial position [Extensible List]	us-gaap:LongTermDebtCurrent
Operating lease liabilities, noncurrent, statement of financial position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent
Financing lease liabilities, noncurrent, statement of financial position [Extensible List]	us-gaap:LongTermDebtNoncurrent

Leases - Maturity Analysis of Lease Liabilities (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Operating Leases
2020	$ 5,210
2021	4,827
2022	4,668
2023	3,247
2024	1,813
Thereafter	7,389
Total undiscounted lease payments	27,154
Less: imputed interest	5,686
Operating Lease, Liability	21,468
Finance Leases
2020	243
2021	243
2022	175
2023	101
2024	82
Thereafter	96
Total undiscounted lease payments	940
Less: imputed interest	128
Total lease liabilities	$ 812

Leases - Schedule of Future Minimum Lease Payments (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Operating
2019	$ 5,071
2020	5,175
2021	4,724
2022	4,681
2023	3,104
2024 and beyond	3,694
Total	26,449
Capital
2019	80
2020	63
2021	67
2022	50
2023	13
2024 and beyond	0
Total	$ 273

Fair Value of Financial Instruments - Schedule of Debt Instruments Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Gross	$ 55,497
Unsecured senior notes \| Fair Value, Measurements, Recurring \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unsecured Senior Notes	0	$ 0
Unsecured senior notes \| Fair Value, Measurements, Recurring \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unsecured Senior Notes	0	0
Unsecured senior notes \| Fair Value, Measurements, Recurring \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unsecured Senior Notes	54,600	52,700
Wells Fargo revolving credit facility \| Fair Value, Measurements, Recurring \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Wells Fargo Credit Agreement	0	0
Wells Fargo revolving credit facility \| Fair Value, Measurements, Recurring \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Wells Fargo Credit Agreement	39,527	54,613
Wells Fargo revolving credit facility \| Fair Value, Measurements, Recurring \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Wells Fargo Credit Agreement	0	0
Unsecured senior notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Gross	55,000	55,000
Unsecured senior notes \| Unsecured senior notes \| Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Gross	54,765	54,712
Wells Fargo revolving credit facility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-Term Debt	39,527	54,613
Wells Fargo revolving credit facility \| Wells Fargo revolving credit facility \| Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-Term Debt	$ 39,527	$ 54,613

Fair Value of Financial Instruments - Schedule of Financial Instruments Measured at Fair Value (Details) - Warrant liability - Fair Value, Measurements, Recurring $ in Thousands	Dec. 31, 2018 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant liability	$ 35,100
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant liability	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant liability	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant liability	$ 35,100

Fair Value of Financial Instruments - Summary of Change in the Estimated Fair Value of Private Placement Warrants (Details) - Warrants - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Balance at beginning of year	$ 35,100	$ 24,700
Change in value of warrants	1,352	10,400
Settlement of warrants	(36,452)	0
Balance at end of year	$ 0	$ 35,100

Fair Value of Financial Instruments - Schedule of Inputs of the Black-Scholes Option Pricing Model (Details) - Black-Scholes option pricing model - Warrant liability - Level 3	Dec. 31, 2018 $ / shares
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contractual term	6 months
Market value of the Common Stock
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Option pricing model input	9.25
Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Option pricing model input	0.026
Estimated price volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Option pricing model input	0.550

Defined Contribution Plans (Details) - USD ($)	12 Months Ended
Defined Contribution Plans (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2019
Retirement Benefits [Abstract]
Employer contributions	$ 0
Employer contributions recorded as a liability	$ 700,000	$ 500,000

Commitments and Contingencies (Details)		1 Months Ended							12 Months Ended
Commitments and Contingencies (Details)	Apr. 22, 2020 USD ($)	Oct. 31, 2019 USD ($)	Feb. 28, 2019 USD ($)	Jan. 31, 2019 USD ($)	Oct. 31, 2018 USD ($)	Mar. 31, 2018 USD ($)	Sep. 30, 2017 USD ($)	Apr. 30, 2017 USD ($) shares	Dec. 31, 2019 USD ($) letter_of_credit	Dec. 31, 2018 USD ($)	Apr. 30, 2019 USD ($)
Loss Contingencies [Line Items]
Number of outstanding letters of credit \| letter_of_credit									7
Outstanding letters of credit amount									$ 3,000,000
Supply Agreement
Loss Contingencies [Line Items]
Minimum product purchase commitment		$ 40,000,000
Product purchases									47,200,000	$ 44,900,000
Asset Purchase Agreement - Alternative Fuel Supply Technology
Loss Contingencies [Line Items]
Payments for commissions						$ 1,200,000	$ 1,200,000		$ 400,000	$ 1,000,000
Guinta v. Power Solutions International, Inc.
Loss Contingencies [Line Items]
Litigation settlement payment				$ 8,500,000
Litigation amount paid			$ 8,500,000
Dorvit v. Winemaster \| Settled Litigation
Loss Contingencies [Line Items]
Range of damages sought											$ 1,900,000
Jerome Treadwell v. The Company
Loss Contingencies [Line Items]
Recovery per negligent violation					$ 1,000
Recovery per intentional or reckless violation					$ 5,000
Don Wilkins V. The Company
Loss Contingencies [Line Items]
Damages sought								$ 2,000,000
Don Wilkins V. The Company \| Restricted Stock
Loss Contingencies [Line Items]
Damages sought (in shares) \| shares								20,000
Subsequent Event \| Don Wilkins V. The Company \| Settled Litigation
Loss Contingencies [Line Items]
Litigation settlement payment	$ 900,000
Subsequent Event \| Don Wilkins V. The Company \| Settled Litigation \| Chief Executive Officer
Loss Contingencies [Line Items]
Litigation settlement payment	$ 1,100,000

Income Taxes - Schedule of Expense (Benefit) for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Current tax (benefit) expense
Federal	$ (238)	$ 198
State	91	27
Foreign	99	0
Total current tax (benefit) expense	(48)	225
Deferred tax expense (benefit)
Federal	329	(149)
State	128	93
Total deferred tax expense (benefit)	457	(56)
Total tax expense	$ 409	$ 169

Income Taxes - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
Income Taxes - Narrative (Details) - USD ($) $ in Thousands	Apr. 23, 2019	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Contingency [Line Items]
Income tax refunds			$ 300	$ 200
Pretax income (loss) including permanently excludable loss			$ 8,700	(54,600)
Period to carry forward general business credits			20 years
Net deferred tax liability			$ 1,105	647
Tax credit carryforwards			6,300
Federal net operating loss carryforwards			11,400
State net operating loss carryforwards			5,000
Income tax benefit			(409)	(169)
Subsequent Event
Income Tax Contingency [Line Items]
Income tax benefit		$ 800
Share Purchase Agreement, Second Amended And Restated Warrant \| Series B Convertible Preferred Stock
Income Tax Contingency [Line Items]
Exercise of private placement warrants (in shares)	4,049,759
Percent ownership of outstanding common stock	51.50%
Private placement warranty liability
Income Tax Contingency [Line Items]
Permanently excludable loss associated with change in valuation of warrants			$ 1,400	$ 10,400

Income Taxes - Reconciliation of Effective Tax Rate to the Statutory Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Amount
Income tax expense (benefit) at federal statutory rate	$ 1,818	$ (11,457)
State income tax, net of federal benefit	618	(1,762)
Non-deductible warrant expense	284	2,184
Other permanent differences	46	70
Research and development tax credits	(715)	(1,058)
Other tax credits	1	(934)
Tax reserve reassessment	25	196
Change in valuation allowance	(2,696)	12,856
Return adjustment	752	0
Stock-based compensation	279	96
Other, net	(3)	(22)
Total tax expense	$ 409	$ 169
Percent
Income tax expense (benefit) at federal statutory rate	21.00%	21.00%
State income tax, net of federal benefit	7.10%	3.20%
Non-deductible warrant expense	3.30%	(4.00%)
Other permanent differences	0.50%	(0.10%)
Research and development tax credits	(8.30%)	1.90%
Other tax credits	(0.00%)	1.70%
Tax reserve reassessment	0.30%	(0.40%)
Change in valuation allowance	(31.10%)	(23.50%)
Return adjustment	8.70%	0.00%
Stock-based compensation	3.20%	(0.20%)
Other, net	0.00%	0.10%
Income tax expense	4.70%	(0.30%)

Income Taxes - Schedule of Significant Components of the Deferred Income Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating loss carryforwards	$ 16,389	$ 19,006
Research and development credits	4,398	3,858
Other state credits	1,922	1,923
Inventory	1,718	2,203
Allowances and bad debts	1,009	840
Accrued warranty	6,344	5,732
Accrued wages and benefits	1,294	413
Other accrued expenses	1,393	5,281
Stock-based compensation	205	649
Capitalized research and development costs	486	770
163(j) disallowed interest	1,688	1,643
Intangible amortization	1,855	2,240
Contract liabilities	3,583	495
Operating lease liability	5,989
Other	356	847
Total deferred tax assets	48,629	45,900
Valuation allowance	(41,709)	(44,405)
Total deferred tax assets, net of valuation allowance	6,920	1,495
Deferred tax liabilities:
ROU operating lease asset	(5,652)	0
Tax depreciation in excess of book depreciation on property, plant and equipment	(2,373)	(2,142)
Total deferred tax liabilities	(8,025)	(2,142)
Net deferred tax liability	$ (1,105)	$ (647)

Income Taxes - Schedule of the Change in Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns
Balance at beginning of year	$ 1,421	$ 1,307
Additions based on tax positions related to the current year	144	193
Reductions for tax positions of prior years	(135)	(79)
Balance at end of year	$ 1,430	$ 1,421

Stockholders' Equity - Common and Treasury Stock and Series B Convertible Preferred Stock (Details)		1 Months Ended	12 Months Ended
	Apr. 23, 2019 shares	Mar. 31, 2017 shares	Dec. 31, 2019 series_of_preferred $ / shares shares	Dec. 31, 2018 $ / shares shares
Common Shares Issued
Common stock, issued, beginning balance (in shares)			19,067,000	19,067,000
Common stock, issued, ending balance (in shares)			23,117,000	19,067,000
Treasury Stock Shares
Treasury stock shares, beginning balance (in shares)			429,000	634,000
Treasury stock shares issued (in shares)			(169,000)	(205,000)
Treasury stock shares, ending balance (in shares)			260,000	429,000
Common Shares Outstanding
Common stock, outstanding, beginning balance (in shares)			18,638,000	18,433,000
Common stock, outstanding, ending balance (in shares)			22,857,000	18,638,000
Series B convertible preferred stock, authorized (in shares)			5,000,000	5,000,000
Series B convertible preferred stock, par value (in dollars per share) \| $ / shares			$ 0.001	$ 0.001
Preferred stock, outstanding (in shares)			0	0
Common Stock
Common Shares Outstanding
Conversion of outstanding stock (in shares)			169,000	205,000
Series B Convertible Preferred Stock
Common Shares Outstanding
Series B convertible preferred stock, authorized (in shares)			5,000,000
Series B convertible preferred stock, par value (in dollars per share) \| $ / shares			$ 0.001
Number of authorized series of preferred stock \| series_of_preferred			2
Share Purchase Agreement, Weichai Transaction \| Common Stock
Common Shares Issued
Shares issued to Weichai (in shares)		2,728,752	4,050,000
Common Shares Outstanding
Shares issued to Weichai (in shares)		2,728,752	4,050,000
Share Purchase Agreement, Second Amended And Restated Warrant \| Series B Convertible Preferred Stock
Common Shares Outstanding
Warrants exercised (in shares)	4,049,759
Percent ownership of outstanding common stock	51.50%

Stock-Based Compensation - Narrative (Details) - shares	12 Months Ended
Stock-Based Compensation - Narrative (Details) - shares	Dec. 31, 2019	Dec. 31, 2013	Dec. 31, 2012
Members of the Board
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	2 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
SARs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share initially made available for awards (in shares)			830,925
Additional shares added to the plan (in shares)		700,000
Share available for issuance of future awards (in shares)	16,174

Stock-Based Compensation - Stock-Based Compensation Expense and Related Income Tax Benefit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement [Abstract]
Stock-based compensation expense	$ 1,248	$ 2,663
Income tax benefit	$ 279	$ 96

Stock-Based Compensation - SAR Awards Narrative (Details) - SARs - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award (in shares)	9,000	60,000
Fair value of restricted stock vested	$ 0.1	$ 0.2
Unrecognized compensation expense	$ 0.2	$ 0.2
Weighted-average period the unrecognized compensation cost is expected to be recognized	1 year 7 months 6 days

Stock-Based Compensation - Schedule of Fair Value Assumptions (Details) - SARs - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Market closing price of the Common Stock (in dollars per share)	$ 7	$ 7.92
Exercise price (in dollars per share)	$ 7.30	$ 7.92
Risk-free interest rate	2.50%	2.60%
Estimated price volatility	77.80%	78.50%
Expected term	6 years 6 months 3 days	6 years 6 months 29 days
Dividend yield	0.00%	0.00%
Weighted average fair value (in dollars per share)	$ 4.89	$ 5.63

Stock-Based Compensation - Schedule of SAR Activity (Details) - SARs - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Shares
Outstanding, beginning balance (in shares)	138,020	83,720
Granted (in shares)	9,000	60,000
Exercised (in shares)	0	0
Forfeited (in shares)	(7,334)	(1,000)
Expired (in shares)	(9,616)	(4,700)
Outstanding, ending balance (in shares)	130,070	138,020	83,720
Exercisable (in shares)	86,736	87,370
Weighted-Average Exercise Price
Outstanding, beginning balance (in dollars per share)	$ 9.66	$ 11.02
Granted (in dollars per share)	7.30	7.92
Exercised (in dollars per share)	0.00	0.00
Forfeited (in dollars per share)	9.81	11.25
Expired (in dollars per share)	10.70	11.25
Outstanding, ending balance (in dollars per share)	9.41	9.66	$ 11.02
Exercisable (in dollars per share)	$ 10.33	$ 11.14
Weighted-Average Remaining Contractual Term (years)
Outstanding (term)	7 years 2 months 16 days	8 years 20 days	8 years 2 months 16 days
Exercisable (term)	5 years 10 months 28 days	6 years 2 months 15 days
Aggregate Intrinsic Value (in thousands)
Outstanding	$ 11	$ 89	$ 1
Exercisable	$ 5	$ 5

Stock-Based Compensation - Schedule of Restricted Stock Activity (Details) - Restricted Stock Awards - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Shares
Outstanding, beginning balance (in shares)	259,286	496,273
Granted (in shares)	48,000	50,000
Forfeited (in shares)	(11,226)	(32,547)
Vested (in shares)	(230,374)	(254,440)
Outstanding, ending balance (in shares)	65,686	259,286
Weighted-Average Grant Date Fair Value
Outstanding, beginning balance (in dollars per share)	$ 12.25	$ 12.20
Granted (in dollars per share)	9.72	10.92
Forfeited (in dollars per share)	14.16	25.95
Vested (in dollars per share)	9.83	10.14
Outstanding, ending balance (in dollars per share)	$ 18.58	$ 12.25

Stock-Based Compensation - Restricted Stock Awards - Narrative (Details) - Restricted Stock Awards - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of restricted stock vested	$ 2.3	$ 2.6
Unrecognized compensation expense	$ 0.9	$ 1.7
Weighted-average period the unrecognized compensation cost is expected to be recognized	2 years 9 months 18 days

Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net income (loss) – basic and diluted	$ 8,248	$ (54,726)
Shares used in computing net income (loss) per share
Weighted-average common shares outstanding - basic (in shares)	21,512	18,585
Effect of dilutive securities (in shares)	18	0
Weighted-average common shares outstanding - diluted (in shares)	21,530	18,585
Earnings (loss) per common share
Earnings (loss) per share — basic (in dollars per share)	$ 0.38	$ (2.94)
Earnings (loss) per share — diluted (in dollars per share)	$ 0.38	$ (2.94)
Antidilutive shares (in shares)	1,400	3,900

Related Party Transactions - Transactions with Joint Ventures (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2015	Dec. 31, 2017
Related Party Transaction [Line Items]
Other income, net		$ (677)	$ (176)
Doosan-PSI, LLC \| Corporate Joint Venture
Related Party Transaction [Line Items]
Investment amount with related party				$ 1,000
Percent of noncontrolling interest					50.00%
MAT-PSI Holdings, LLC \| Green Power \| Corporate Joint Venture
Related Party Transaction [Line Items]
Ownership percentage	100.00%
Investment amount with related party	$ 900
Percent of noncontrolling interest	50.00%

Related Party Transactions - Transactions with Related Individuals (Details) - Former Chairman Of The Board, Chief Executive Officer And President And Non-Executive Chief Strategy Officer $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Related Party Transaction [Line Items]
Purchases from related party	$ 0.4
Industrial Electronic Controls
Related Party Transaction [Line Items]
Percent of noncontrolling interest	50.00%

Subsequent Events (Details) - Subsequent Event	Apr. 24, 2020
Minimum
Subsequent Event [Line Items]
Reduced pay for salaried employees, percent	10.00%
Maximum
Subsequent Event [Line Items]
Reduced pay for salaried employees, percent	30.00%

Label	Element	Value
Accounting Standards Update 2014-09 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 1,713,000
Accounting Standards Update 2014-09 [Member] \| Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 1,713,000