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Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2017	Oct. 26, 2017
Document and Entity Information
Entity Registrant Name	Clean Energy Fuels Corp.
Entity Central Index Key	0001368265
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding (in shares)		151,085,558
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 45,312	$ 36,119
Restricted cash	1,463	6,996
Short-term investments	151,521	73,718
Accounts receivable, net of allowance for doubtful accounts of $1,063 and $2,336 as of December 31, 2016 and September 30, 2017, respectively	61,001	79,432
Other receivables	16,253	21,934
Inventory	44,624	29,544
Prepaid expenses and other current assets	10,838	14,021
Total current assets	331,012	261,764
Land, property and equipment, net	363,773	483,923
Notes receivable and other long-term assets, net	25,619	16,377
Investments in other entities	2,542	3,475
Goodwill	68,082	93,018
Intangible assets, net	7,491	38,700
Total assets	798,519	897,257
Current liabilities:
Current portion of debt and capital lease obligations	29,247	5,943
Accounts payable	16,215	23,637
Accrued liabilities	41,990	52,601
Deferred revenue	6,487	7,041
Total current liabilities	93,939	89,222
Long-term portion of debt and capital lease obligations	185,597	241,433
Long-term debt, related party	40,000	65,000
Other long-term liabilities	13,416	7,915
Total liabilities	332,952	403,570
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.0001 par value. Authorized 1,000,000 shares; issued and outstanding no shares	0	0
Common stock, $0.0001 par value. Authorized 224,000,000 shares; issued and outstanding 145,538,063 shares and 151,009,700 shares at December 31, 2016 and September 30, 2017, respectively	15	15
Additional paid-in capital	1,110,158	1,090,361
Accumulated deficit	(655,223)	(603,836)
Accumulated other comprehensive loss	(12,392)	(17,675)
Total Clean Energy Fuels Corp. stockholders’ equity	442,558	468,865
Noncontrolling interest in subsidiary	23,009	24,822
Total stockholders’ equity	465,567	493,687
Total liabilities and stockholders’ equity	$ 798,519	$ 897,257

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 2,336	$ 1,063
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, authorized (in shares)	1,000,000	1,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, authorized (in shares)	224,000,000	224,000,000
Common stock, issued (in shares)	151,009,700	145,538,063
Common stock, outstanding (in shares)	151,009,700	145,538,063

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenue:
Product revenue	$ 67,669	$ 84,456	$ 211,747	$ 263,179
Service revenue	14,123	12,561	40,552	37,645
Total revenue	81,792	97,017	252,299	300,824
Cost of sales (exclusive of depreciation and amortization shown separately below):
Product cost of sales	52,884	55,481	158,306	170,746
Service cost of sales	7,283	6,377	20,066	19,095
Inventory valuation provision	13,158	0	13,158	0
Selling, general and administrative	24,798	25,888	71,875	76,744
Depreciation and amortization	14,104	14,801	43,757	44,682
Asset impairments and other charges	60,666	0	60,666	0
Total operating expenses	172,893	102,547	367,828	311,267
Operating loss	(91,101)	(5,530)	(115,529)	(10,443)
Interest expense	(4,270)	(6,406)	(13,466)	(23,843)
Interest income	465	123	1,156	579
Other income (expense), net	4	(109)	(28)	(6)
Loss from equity method investments	(30)	(13)	(100)	(20)
Gain (loss) from extinguishment of debt	0	(668)	3,195	25,375
Gain from sale of certain assets of subsidiary	0	0	69,886	0
Loss before income taxes	(94,932)	(12,603)	(54,886)	(8,358)
Income tax benefit (expense)	44	(416)	2,183	(1,229)
Net loss	(94,888)	(13,019)	(52,703)	(9,587)
Loss attributable to noncontrolling interest	747	391
Net loss attributable to Clean Energy Fuels Corp.	$ (94,141)	$ (12,628)	$ (50,890)	$ (8,270)
Loss per share:
Basic (in dollars per share)	$ (0.62)	$ (0.10)	$ (0.34)	$ (0.07)
Diluted (in dollars per share)	$ (0.62)	$ (0.10)	$ (0.34)	$ (0.07)
Weighted-average common shares outstanding:
Basic (in shares)	150,927,825	130,436,038	150,128,204	112,819,041
Diluted (in shares)	150,927,825	130,436,038	150,128,204	112,819,041

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net loss	$ (94,888)	$ (13,019)	$ (52,703)	$ (9,587)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments, net of $0 tax in 2016 and 2017	252	(449)	289	2,185
Foreign currency adjustments on intra-entity long-term investments, net of $0 tax in 2016 and 2017	2,919	(885)	5,033	3,024
Unrealized gains (losses) on available-for-sale securities, net of $0 tax in 2016 and 2017	70	(11)	(39)	66
Total other comprehensive income (loss)	3,241	(1,345)	5,283	5,275
Comprehensive loss	(91,647)	(14,364)	(47,420)	(4,312)
Clean Energy Fuels Corp.
Net loss	(94,141)	(12,628)	(50,890)	(8,270)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments, net of $0 tax in 2016 and 2017	252	(449)	289	2,185
Foreign currency adjustments on intra-entity long-term investments, net of $0 tax in 2016 and 2017	2,919	(885)	5,033	3,024
Unrealized gains (losses) on available-for-sale securities, net of $0 tax in 2016 and 2017	70	(11)	(39)	66
Total other comprehensive income (loss)	3,241	(1,345)	5,283	5,275
Comprehensive loss	(90,900)	(13,973)	(45,607)	(2,995)
Noncontrolling Interest
Net loss	(747)	(391)	(1,813)	(1,317)
Other comprehensive income (loss), net of tax:
Comprehensive loss	$ (747)	$ (391)	$ (1,813)	$ (1,317)

Condensed Consolidated Statements of Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Foreign currency translation adjustments, tax	$ 0	$ 0	$ 0	$ 0
Foreign currency adjustments on intra-entity long-term investments, tax	0	0	0	0
Unrealized (losses) gains on available-for-sale securities, tax	$ 0	$ 0	$ 0	$ 0

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net loss	$ (52,703)	$ (9,587)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	43,757	44,682
Provision for doubtful accounts, notes and inventory	16,156	2,504
Stock-based compensation expense	6,604	6,533
Amortization of debt issuance cost	647	1,217
Gain on extinguishment of debt	(3,195)	(25,375)
Gain from sale of certain assets of subsidiary	(69,886)	0
Non-cash portion of asset impairments and other charges	58,119	0
Changes in operating assets and liabilities:
Accounts and other receivables	23,936	31,134
Inventory	494	(1,043)
Prepaid expenses and other assets	794	(178)
Accounts payable	(9,426)	(940)
Accrued expenses and other	(20,148)	(4,702)
Net cash provided by (used in) operating activities	(4,851)	44,245
Cash flows from investing activities:
Purchases of short-term investments	(227,212)	(88,660)
Maturities and sales of short-term investments	149,044	113,852
Purchases and deposits on property and equipment	(27,529)	(16,663)
Loans made to customers	(535)	(2,326)
Payments on and proceeds from sales of loans receivable	978	575
Restricted cash	1,578	(267)
Cash received from sale of certain assets of subsidiary, net of cash transferred	154,489	0
Investments in other entities	(1,929)	0
Capital from equity method investment	0	3,031
Nonrefundable customer deposit	8,350	0
Net cash provided by investing activities	57,234	9,542
Cash flows from financing activities:
Issuances of common stock	10,767	68,867
Fees paid for issuances of common stock	(638)	(1,340)
Payment to holders of stock options in subsidiary	(8,605)	0
Proceeds from debt instruments	7,561	2,460
Proceeds from revolving line of credit	308	50,008
Repayment of borrowing under revolving line of credit	(23,670)	(50,014)
Repayment of capital lease obligations and debt instruments	(29,664)	(127,213)
Net cash used in financing activities	(43,941)	(57,232)
Effect of exchange rates on cash and cash equivalents	751	1,276
Net increase in cash and cash equivalents	9,193	(2,169)
Cash and cash equivalents, beginning of period	36,119	43,724
Cash and cash equivalents, end of period	45,312	41,555
Supplemental disclosure of cash flow information:
Income taxes paid	363	1,176
Interest paid, net of approximately $712 and $73 capitalized, respectively	$ 14,351	$ 21,275

Condensed Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Statement of Cash Flows [Abstract]
Interest paid, capitalized	$ 73	$ 712

General	9 Months Ended
General	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
General	General Nature of Business Clean Energy Fuels Corp., together with its majority and wholly owned subsidiaries (hereinafter collectively referred to as the "Company," unless the context or the use of the term indicates or requires otherwise) is engaged in the business of selling natural gas as an alternative fuel for vehicle fleets and related natural gas fueling solutions to its customers, primarily in the United States and Canada. The Company's principal business is supplying renewable natural gas ("RNG"), compressed natural gas (“CNG”) and liquefied natural gas (“LNG”) for light, medium and heavy-duty vehicles and providing operation and maintenance ("O&M") services for natural gas fueling stations. As a comprehensive solution provider, the Company also designs, builds, operates, and maintains fueling stations; manufactures, sells and services non-lubricated natural gas fueling compressors and other equipment used in CNG stations and LNG stations; offers assessment, design and modification solutions to provide operators with code-compliant service and maintenance facilities for natural gas vehicle fleets; transports and sells CNG and LNG to industrial and institutional energy users who do not have direct access to natural gas pipelines; procures and sells RNG; sells tradable credits it generates by selling natural gas and RNG as a vehicle fuel, including credits under the California and the Oregon Low Carbon Fuel Standards (collectively, "LCFS Credits") and Renewable Identification Numbers ("RIN Credits" or "RINs") under the federal Renewable Fuel Standard Phase 2; helps its customers acquire and finance natural gas vehicles; and obtains federal, state and local credits, grants and incentives. Basis of Presentation The accompanying interim unaudited condensed consolidated financial statements include the accounts of the Company and its subsidiaries, and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to state fairly the Company’s financial position, results of operations, comprehensive loss and cash flows as of and for the three and nine months ended September 30, 2016 and 2017. All intercompany accounts and transactions have been eliminated in consolidation. The three and nine month periods ended September 30, 2016 and 2017 are not necessarily indicative of the results to be expected for the year ending December 31, 2017 or for any other interim period or for any future year. Certain information and disclosures normally included in the notes to the financial statements have been condensed or omitted pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”), but the resultant disclosures contained herein are in accordance with accounting principles generally accepted in the United States of America (“US GAAP”) as they apply to interim reporting. The condensed consolidated financial statements should be read in conjunction with the consolidated financial statements as of and for the year ended December 31, 2016 that are included in the Company’s Annual Report on Form 10-K filed with the SEC on March 7, 2017. Reclassifications Certain prior period line items in the condensed consolidated statements of operations have been reclassified to conform to the classifications used to prepare the condensed consolidated financial statements for the period ended September 30, 2017. These reclassifications had no material impact on the Company’s financial position, results of operations, or cash flows as previously reported. Use of Estimates The preparation of condensed consolidated financial statements in conformity with US GAAP requires management to make estimates and assumptions that affect the amounts reported in the accompanying unaudited condensed consolidated financial statements and these notes. Actual results could differ from those estimates and may result in material effects on the Company’s operating results and financial position.

Asset Impairments, Other Charges, and Inventory Valuation Provision

9 Months Ended

Sep. 30, 2017

Restructuring and Related Activities [Abstract]

Asset Impairments, Other Charges, and Inventory Valuation Provision

In light of continuing low oil prices and the current state of natural gas vehicle adoption, during the three months ended September 30, 2017, the Company undertook an evaluation of its operations with the intent of minimizing and eliminating assets it believes are underperforming. As a result of this evaluation, the Company identified certain of its fueling stations where the current and projected natural gas volume and profitability levels are not expected to be sufficient to support the Company’s investment in the fueling station assets, and the Company decided to close these stations by the end of 2017. The Company also reduced its workforce and took other steps to reduce overhead costs in the three months ended September 30, 2017 as a result of this evaluation, in an effort to lower its operating expenses going forward. In addition, this evaluation resulted in a strategic shift in how the Company viewed its natural gas compressor business, Clean Energy Compression Corp. ("CECC").The Company determined to seek a strategic partner for CECC and to position CECC to benefit from consolidation in the natural gas compressor sector, in an effort to increase CECC’s scale and reach and improve the financial prospects of the Company’s investment in CECC. As a result of these decisions and the steps taken to implement them, the Company incurred, on a pre-tax basis, aggregate cash and non-cash charges of $60,666 related to asset impairments and other charges in addition to a $13,158 non-cash inventory valuation charge (see Note 9 for more information), during the three and nine months ended September 30, 2017.

The following table summarizes these charges:



	Three and Nine Months Ended September 30, 2017
Workforce reduction and related charges	$	3,057
CECC asset impairments	32,274
Station closures and related charges	25,335
Total asset impairments and other charges	$	60,666
Inventory valuation provision	13,158
Total charges	$	73,824

Workforce Reduction and Related Charges

As a result of the workforce reduction, severance of $2,757 was incurred for terminated employees and $300 in stock-based compensation expense was incurred for the acceleration of certain stock options and awards.

Impairments of Long-Lived Assets

The Company reviews the carrying value of its long-lived assets, including intangible assets with finite useful lives, for impairment whenever events or changes in circumstances indicate that the carrying value of an asset or asset group may not be recoverable. Events that could result in an impairment review include, among others, a significant decrease in the operating performance of a long-lived asset or the decision to close a fueling station. Impairment testing involves a comparison of the sum of the undiscounted future cash flows of the asset or asset group to its carrying amount. If the sum of the undiscounted future cash flows exceeds the carrying amount, then no impairment exists. If the carrying amount exceeds the sum of the undiscounted future cash flows, then a second step is performed to determine the amount of impairment, if any, to be recognized. An impairment loss is recognized to the extent that the carrying amount of the asset or asset group exceeds its fair value. The fair value of the asset or asset group is based on estimated discounted future cash flows of the asset or asset group using a discount rate commensurate with the related risk. The estimate of future cash flows requires management to make assumptions and to apply judgment, including forecasting future sales and expenses and estimating useful lives of the assets. These estimates can be affected by a number of factors, including, among others, future results, demand, and economic conditions, many of which can be difficult to predict.

CECC: Asset Impairment Charges

Due to the continued low global demand for compressors, and the decision to seek a strategic partner for CECC, the Company’s management determined that an impairment indicator was present for the long-lived assets of CECC. Recoverability was tested using future cash flow projections based on management’s long-term estimates of market conditions. Based on the results of this test, the sum of the undiscounted future cash flows was less than the carrying value of the CECC asset group. As a result, these long-lived assets were written down to their respective fair values, resulting in an impairment charge of $32,274. Fair value was based on expected future cash flows using Level 3 inputs under the Financial Accounting Standards Board’s (“FASB”) Accounting Standard Codification (“ASC”) Topic 820. The cash flows are those expected to be generated by market participants, discounted at an appropriate rate for the risks inherent in those cash flow projections. If actual results, market and economic conditions, including interest rates, and other factors are not consistent with management’s estimates and assumptions used in these calculations, the Company may be exposed to additional impairment losses.

The following table represents intangible assets of CECC as of December 31, 2016 and September 30, 2017, respectively, as well as their useful lives, which continued to be appropriate and were not changed:



	December 31, 2016		September 30, 2017		Remaining Useful Life (Years)
Technology	$	29,060	$	3,151	13
Customer relationships	2,239		117		1
Trademark and trade names	1,842		201		3
Total	$	33,141	$	3,469

Station Closures and Related Charges

In the three months ended September 30, 2017, the Company decided to close 42 fueling stations by December 31, 2017 which are performing below management’s expectations based on volume and profitability levels. As a result, these station assets, which had an aggregate carrying value of $23,270 were written down to their respective fair values of $2,886 on an aggregate basis, resulting in charges of $20,384. The fair values of these assets were determined using the cost approach.

Due to these stations being closed before their initially intended date the Company's management assessed whether impairment indicators were present for the long-lived assets of the remaining stations. The Company determined there were no indicators of impairment present amongst the remaining stations and no further steps were required for evaluation.

In addition, certain of these station closures triggered related other charges totaling $4,951, which consists of write-offs for any deferred losses, lease termination fees, and an increase in asset retirement obligations ("AROs").

Inventory Valuation Provision

Inventory consists of raw materials and spare parts, work in process and finished goods and is stated at the lower of cost (first-in, first-out) or market. The Company writes down the carrying value of its inventory to net realizable value for estimated obsolescence or unmarketable inventory in an amount equal to the difference between the cost of inventory and its estimated realizable value based upon assumptions about future demand and market conditions, among other factors.

As a result of the Company's valuation process to minimize and eliminate under-performing station assets, the Company determined that $27,198 of certain station parts which historically were classified as construction in progress within Land, property, and equipment, net in the condensed consolidated balance sheets, are now reported as Inventory as they will primarily be used for stations to be sold. Subsequently, the Company determined a lower of cost or market non-cash charge of $7,804 for these station parts. Additionally, in conjunction with its decision to seek a strategic partner for CECC, the Company incurred a lower of cost or market non-cash charge of $5,354 for the inventory of CECC. The aggregate amount of $13,158 is reported as Inventory valuation provision in the condensed consolidated statements of operations during the three and nine months ended September 30, 2017.

Cash Related Charges

The following table summarizes the total charges that will be settled with cash payments and their related liability balances as of September 30, 2017:



	Charges		Cash Payments Made in the Three Months Ended September 30, 2017			Balance as of September 30, 2017
Employee severance	$	2,757	$	(2,547	)	$	210
Lease termination fees and AROs for station closures	3,861		—			3,861
	$	6,618				$	4,071

Goodwill

As a result of the asset impairments described above, the Company determined that sufficient indicators of potential impairment existed to require an interim goodwill test of its one reporting unit prior to the annual test performed in the fourth quarter of 2017. The goodwill test is performed by computing the fair value of the reporting unit and comparing it to the carrying value.

Based on the results of this test, the Company has determined that it continues to be a single reporting unit and, based upon step one of the two-step goodwill test, has concluded it is more likely than not that the fair value of its reporting unit exceeds its carrying amount and thus no further quantitative analysis was warranted.

Acquisitions and Divestitures	9 Months Ended
Acquisitions and Divestitures	Sep. 30, 2017
Business Combinations [Abstract]
Acquisitions and Divestitures	Acquisitions and Divestitures On February 27, 2017, Clean Energy Renewable Fuels ("Renewables"), a subsidiary of the Company, entered into an asset purchase agreement (the “APA”) with BP Products North America, Inc. (“BP”), pursuant to which Renewables agreed to sell to BP certain assets relating to its RNG production business (the “Asset Sale”), consisting of Renewables’ two existing RNG production facilities, Renewables’ interest in the RNG Ventures (as defined in Note 11) and Renewables’ third-party RNG supply contracts (the “Assets”). The Asset Sale was completed on March 31, 2017 for a sale price of $155,511, plus BP assumed the obligations under the Canton Bonds (as defined in Note 13), which totaled $8,820 as of March 31, 2017. On March 31, 2017 BP paid Renewables $30,000 in cash and delivered to Renewables a promissory note with a principal amount of $123,487 (the "BP Note") which was paid in full on April 3, 2017. In addition, as a result of the determination of certain post-closing adjustments, (i) BP paid Renewables an additional $2,010 on June 22, 2017, and (ii) the gain recorded from the Asset Sale was reduced by $762. Pursuant to the APA, the valuation date of the Asset Sale was January 1, 2017, and as a result, the APA included certain adjustments to the purchase price to reflect a determination of the amount of cash accumulated by Renewables from the valuation date to the closing date, net of permitted cash outflows. Control of the Assets was not transferred until the Asset Sale was completed on March 31, 2017. Accordingly, the full operating results of Renewables are included in the condensed consolidated statement of operations through the three months ended March 31, 2017. In addition, under the APA, BP is required, following the closing of the Asset Sale, to pay Renewables up to an additional $25,000 in cash over a five-year period if certain performance criteria relating to the Assets are met. The Company incurred $3,695 in transaction fees in connection with the Asset Sale, and subsequent to March 31, 2017, the Company paid $8,605 in cash and issued 770,269 shares of the Company's common stock, collectively valued at $1,964, to holders of options to purchase membership units in Renewables. The net proceeds from the Asset Sale, net of $1,007 cash transferred to BP, were $142,190. Following completion of the Asset Sale, Renewables and the Company are continuing to procure RNG from BP under a long-term supply contract and from other RNG suppliers, and resell such RNG through the Company's natural gas fueling infrastructure as Redeem™, the Company's RNG vehicle fuel. The Company also collects royalties from BP on gas purchased from BP and sold as Redeem™ at the Company's stations, which royalty is in addition to any payment obligation of BP under the APA. The Asset Sale resulted in a total gain of $69,886 that was recorded in gain from sale of certain assets of subsidiary in the Company's condensed consolidated statement of operations for the nine months ended September 30, 2017. Included in the determination of the total gain is goodwill of $26,576 that was allocated to the disposed assets based on the relative fair values of the assets disposed and the portion of the reporting unit that was retained. The Company determined that the Asset Sale did not meet the definition of a discontinued operation because the disposal did not represent a significant disposal nor was the disposal a strategic shift in the Company's strategy.

- Definition

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Section 50
-Paragraph 5
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Paragraph 4
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-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1486-128463

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-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=73530397&loc=d3e4845-128472

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-Section 50
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-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e7000-128479

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-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 2
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
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-URI http://asc.fasb.org/extlink&oid=73530397&loc=d3e4926-128472

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 4A
-URI http://asc.fasb.org/extlink&oid=73530397&loc=SL65897772-128472

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1383-128463

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6996-128479

+ Details

Cash and Cash Equivalents	9 Months Ended
Cash and Cash Equivalents	Sep. 30, 2017
Cash and Cash Equivalents [Abstract]
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with maturities of three months or less on the date of acquisition to be cash equivalents. The Company places its cash and cash equivalents with high credit quality financial institutions. At times, such investments may be in excess of the Federal Deposit Insurance Corporation (“FDIC”), Canadian Deposit Insurance Corporation (“CDIC”) and other foreign insurance limits. Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash deposits. The amounts in excess of FDIC, CDIC and other foreign insurance limits were approximately $34,439 and $43,200 at December 31, 2016 and September 30, 2017, respectively.

- Definition

The entire disclosure for cash and cash equivalent footnotes, which may include the types of deposits and money market instruments, applicable carrying amounts, restricted amounts and compensating balance arrangements. Cash and equivalents include: (1) currency on hand (2) demand deposits with banks or financial institutions (3) other kinds of accounts that have the general characteristics of demand deposits (4) short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Generally, only investments maturing within three months from the date of acquisition qualify.

+ References + Details

Restricted Cash

9 Months Ended

Sep. 30, 2017

Restricted Cash and Investments, Current [Abstract]

Restricted Cash

The Company classifies restricted cash as short-term and a current asset if the cash is expected to be used in operations within a year or to acquire a current asset. Otherwise, the restricted cash is classified as long-term. Short-term restricted cash at December 31, 2016 and September 30, 2017 consisted of the following:



	December 31, 2016		September 30, 2017
Short-term restricted cash:
Standby letters of credit	$	1,753	$	1,463
Canton Bonds (see Note 13)	3,665		—
Held in escrow	1,578		—
Total short-term restricted cash	$	6,996	$	1,463

Investments

9 Months Ended

Sep. 30, 2017

Investments, Debt and Equity Securities [Abstract]

Investments

Available-for-sale securities are carried at fair value, inclusive of unrealized gains and losses. Unrealized gains and losses are included in other comprehensive income (loss), net of applicable income taxes. Gains or losses on sales of available-for-sale securities are recognized on the specific identification basis. All of the Company's short-term investments are classified as available-for-sale securities.

The Company reviews available-for-sale securities for other-than-temporary declines in fair value below their cost basis each quarter and whenever events or changes in circumstances indicate that the cost basis of an asset may not be recoverable. This evaluation is based on a number of factors, including the length of time and the extent to which the fair value has been below its cost basis and adverse conditions related specifically to the security, including any changes to the credit rating of the security. As of September 30, 2017, the Company believes its carrying values for its available-for-sale securities are properly recorded.

Short-term investments as of December 31, 2016 consisted of the following:



	Amortized Cost		Gross Unrealized Losses			Estimated Fair Value
Municipal bonds and notes	$	8,791	$	(4	)	$	8,787
Corporate bonds	21,517		(7		)	21,510
Certificate of deposits	43,421		—			43,421
Total short-term investments	$	73,729	$	(11	)	$	73,718

Short-term investments as of September 30, 2017 consisted of the following:



	Amortized Cost		Gross Unrealized Losses			Estimated Fair Value
Municipal bonds and notes	$	21,470	$	(73	)	$	21,397
Zero coupon bonds	69,192		(59		)	69,133
Corporate bonds	39,596		(13		)	39,583
Certificate of deposits	21,408		—			21,408
Total short-term investments	$	151,666	$	(145	)	$	151,521

- Definition

The entire disclosure for investments in certain debt and equity securities.

+ References + Details

Fair Value Measurements

9 Months Ended

Sep. 30, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurements

The Company follows the authoritative guidance for fair value measurements with respect to assets and liabilities that are measured at fair value on a recurring basis and non-recurring basis. Under the standard, fair value is defined as the exit price, or the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants, as of the measurement date. The standard also establishes a hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the most observable inputs be used when available. Observable inputs are inputs market participants would use in valuing the asset or liability developed based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the factors market participants would use in valuing the asset or liability developed based upon the best information available in the circumstances. The hierarchy consists of the following three levels: Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities; Level 2 inputs include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, and inputs (other than quoted prices) that are observable for the asset or liability, either directly or indirectly; Level 3 inputs are unobservable inputs for the asset or liability. Categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement.

As of September 30, 2017, the Company's financial instruments consisted of available-for-sale securities, liability-classified warrants, and debt instruments. The Company’s available-for-sale securities are classified within Level 2 because they are valued using the most recent quoted prices for identical assets in markets that are not active and quoted prices for similar assets in active markets. The liability-classified warrants are classified within Level 3 because the Company uses the Black-Scholes option pricing model to estimate the fair value based on inputs that are not observable in any market. The fair values of the Company's debt instruments approximated their carrying values as of December 31, 2016 and September 30, 2017. See Note 13 for more information about the Company's debt instruments. There were no transfers of assets between Level 1, Level 2, or Level 3 of the fair value hierarchy as of December 31, 2016 and September 30, 2017, respectively.

The following tables provide information by level for assets and liabilities that are measured at fair value on a recurring basis as of December 31, 2016 and September 30, 2017, respectively:



Description	Balance at December 31, 2016		Level 1		Level 2		Level 3
Assets:
Available-for-sale securities(1):
Municipal bonds and notes	$	8,787	$	—	$	8,787	$	—
Corporate bonds	21,510		—		21,510		—
Certificate of deposits	43,421		—		43,421		—
Liabilities:
Warrants(2)	581		—		—		581



Description	Balance at September 30, 2017		Level 1		Level 2		Level 3
Assets:
Available-for-sale securities(1):
Municipal bonds and notes	$	21,397	$	—	$	21,397	$	—
Zero coupon bonds	69,133		—		69,133		—
Corporate bonds	39,583		—		39,583		—
Certificate of deposits	21,408		—		21,408		—
Liabilities:
Warrants(2)	543		—		—		543

(1) Included in short-term investments in the condensed consolidated balance sheets. See Note 6 for more information.

(2) Included in accrued liabilities and other long-term liabilities in the condensed consolidated balance sheets.

Non-Financial Assets

During the three and nine months ended September 30, 2017, long-lived assets held and used with a carrying value of $59,367 were written down to their fair value of $6,709, resulting in charges of $52,658. The fair value of these assets was determined using Level 3 inputs. See Note 2 for more information.

No impairments were incurred during 2016.

- 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

Other Receivables

9 Months Ended

Sep. 30, 2017

Receivables [Abstract]

Other Receivables

Other receivables as of December 31, 2016 and September 30, 2017 consisted of the following:



	December 31, 2016		September 30, 2017
Loans to customers to finance vehicle purchases	$	7,416	$	6,896
Accrued customer billings	4,308		6,328
Fuel tax credits	6,358		—
Other	3,852		3,029
Total other receivables	$	21,934	$	16,253

- Definition

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

+ References + Details

Inventory

9 Months Ended

Sep. 30, 2017

Inventory Disclosure [Abstract]

Inventory

Inventories as of December 31, 2016 and September 30, 2017 consisted of the following:



	December 31, 2016		September 30, 2017
Raw materials and spare parts (1)	$	24,843	$	42,487
Work in process	845		806
Finished goods	3,856		1,331
Total inventories	$	29,544	$	44,624


(1)	As of September 30, 2017, this amount also includes $19,394 for certain station parts which historically were classified as construction in progress within Land, property, and equipment, net, that are now reported in Inventory in the condensed consolidated balance sheets because they will primarily be used for stations to be sold. See Note 2 for more information.

Land, Property and Equipment

9 Months Ended

Sep. 30, 2017

Property, Plant and Equipment [Abstract]

Land, Property and Equipment

Land, property and equipment as of December 31, 2016 and September 30, 2017 consisted of the following:



	December 31, 2016			September 30, 2017
Land	$	2,858		$	2,858
LNG liquefaction plants	94,634			94,633
RNG plants (1)	47,545			—
Station equipment (2)	341,605			298,681
Trailers	54,985			59,312
Other equipment (2)	93,118			94,389
Construction in progress (2) (3)	117,662			79,366
	752,407			629,239
Less: accumulated depreciation	(268,484		)	(265,466		)
Total land, property and equipment, net	$	483,923		$	363,773

(1) The RNG plants were sold in the Asset Sale (see Note 3 for more information).


(2)	Certain of these assets were written down during the three months ended September 30, 2017 (see Note 2 for more information).


(3)	As of September 30, 2017, $19,394 of certain station parts which historically were classified as construction in progress within Land, property, and equipment, net, that are now reported in Inventory in the condensed consolidated balance sheets because they will primarily be used for stations to be sold.

Included in land, property and equipment are capitalized software costs of $25,728 and $27,056 as of December 31, 2016 and September 30, 2017, respectively. The accumulated amortization of the capitalized software costs is $17,237 and $20,371 as of December 31, 2016 and September 30, 2017, respectively.

The Company recorded amortization expense related to the capitalized software costs of $824 and $1,140 during the three months ended September 30, 2016 and 2017, respectively, and $2,609 and $3,134 during the nine months ended September 30, 2016 and 2017, respectively.

As of September 30, 2016 and 2017, $4,139 and $2,007, respectively, are included in accounts payable and accrued liabilities balances, which amounts are related to purchases of property and equipment. These amounts are excluded from the condensed consolidated statements of cash flows as they are non-cash investing activities.

Investments in Other Entities and Noncontrolling Interest in a Subsidiary	9 Months Ended
	Sep. 30, 2017
Business Combinations [Abstract]
Investments in Other Entities and Noncontrolling Interest in a Subsidiary	Investments in Other Entities and Noncontrolling Interest in a Subsidiary RNG Ventures In November 2016, Renewables entered into agreements to form joint ventures with Aria Energy Operating LLC ("Aria"), a developer of RNG production facilities, to develop RNG production facilities at a Republic Services landfill in Oklahoma City, Oklahoma and an Advanced Disposal landfill near Atlanta, Georgia. These joint ventures are referred to as the "RNG Ventures." Renewables' interest in the RNG Ventures was transferred to BP upon completion of the Asset Sale (see Note 3 for more information); however, Renewables retained the right to purchase 100% of the RNG that will be produced by the production facilities to be developed by the RNG Ventures for the vehicle fuels market. The Company accounted for its interest in the RNG Ventures using the equity method of accounting as the Company had the ability to exercise significant influence over these operations. The Company had an investment balance of $833 and $0 in the RNG Ventures as of December 31, 2016 and September 30, 2017, respectively. MCEP On September 16, 2014, the Company formed a joint venture with Mansfield Ventures LLC (“Mansfield”) called Mansfield Clean Energy Partners LLC (“MCEP”), which is designed to provide natural gas fueling solutions to bulk fuel haulers in the United States. The Company and Mansfield each have a 50% ownership interest in MCEP. The Company accounts for its interest in MCEP using the equity method of accounting, as the Company has the ability to exercise significant influence over MCEP’s operations. The Company recorded loss from this investment of $13 and $30 for the three months ended September 30, 2016 and 2017, respectively, and $20 and $100 for the nine months ended September 30, 2016 and 2017, respectively. Additionally, on June 28, 2016, the Company received a return of capital of $3,031 with no change in ownership interest. The Company has an investment balance of $1,642 and $1,542 at December 31, 2016 and September 30, 2017, respectively. NG Advantage On October 14, 2014, the Company entered into a Common Unit Purchase Agreement (“UPA”) with NG Advantage, LLC (“NG Advantage”) for a 53.3% controlling interest in NG Advantage. NG Advantage is engaged in the business of transporting CNG in high-capacity trailers to industrial and institutional energy users, such as hospitals, food processors, manufacturers and paper mills that do not have direct access to natural gas pipelines. The Company viewed the acquisition as a strategic investment in the expansion of the Company’s initiative to deliver natural gas to industrial and institutional energy users. The results of NG Advantage’s operations have been included in the Company’s consolidated financial statements since October 14, 2014. On July 14, 2017, the Company contributed to NG Advantage all of its right, title and interest in and to a CNG station located in Milton, Vermont. The Company had purchased this CNG station from NG Advantage in October 2014 in connection with the UPA, and at that time, the Company entered into a lease agreement with NG Advantage to lease the station back to NG Advantage. This lease agreement was terminated contemporaneously with the contribution of the station to NG Advantage in July 2017. As consideration for the contribution, NG Advantage issued to the Company Series A Preferred Units with an aggregate value of $7,500. The Series A Preferred Units provide for an accrued return in the event of a liquidation event with respect to NG Advantage and will convert into common units of NG Advantage if and when it completes a future equity financing that satisfies certain specified conditions, but the Series A Preferred Units do not, in themselves, increase the Company's controlling interest in NG Advantage. As a result, following the contribution, the Company's controlling interest in NG Advantage remains at 53.3%. The Company recorded a loss from the noncontrolling interest in NG Advantage of $391 and $747 for the three months ended September 30, 2016 and 2017, respectively, and $1,317 and $1,813 for the nine months ended September 30, 2016 and 2017, respectively. The noncontrolling interest was $24,822 and $23,009 as of December 31, 2016 and September 30, 2017, respectively.

Accrued Liabilities

9 Months Ended

Sep. 30, 2017

Payables and Accruals [Abstract]

Accrued Liabilities

Accrued liabilities as of December 31, 2016 and September 30, 2017 consisted of the following:



	December 31, 2016		September 30, 2017
Accrued alternative fuels incentives (1)	$	9,840	$	2,270
Accrued employee benefits	4,317		3,999
Accrued interest	1,849		39
Accrued gas and equipment purchases	11,657		10,220
Accrued property and other taxes	4,572		4,164
Salaries and wages (2)	12,293		8,636
Other (3)	8,073		12,662
Total accrued liabilities	$	52,601	$	41,990


(1)	Includes the amount of RINs and LCFS Credits and, as of December 31, 2016, the amount of a federal alternative fuels tax credit ("VETC") payable to third parties. VETC expired as of December 31, 2016, and as a result, no VETC amounts were accrued as of September 30, 2017 (see Note 18 for more information about VETC).


(2)	The amount as of September 30, 2017 includes severance accruals related to a workforce reduction during the three months ended September 30, 2017 (see Note 2 for more information).


(3)	The amount as of September 30, 2017 also includes lease termination fees and AROs related to closure of certain fueling stations (see Note 2 for more information).

Debt

9 Months Ended

Sep. 30, 2017

Debt Disclosure [Abstract]

Debt

Debt and capital lease obligations as of December 31, 2016 and September 30, 2017 consisted of the following and are further discussed below:



	December 31, 2016
	Principal Balances			Unamortized Debt Financing Costs			Balance, Net of Financing Costs
7.5% Notes (1)	$	150,000		$	274		$	149,726
5.25% Notes	110,450			1,088			109,362
Plains Credit Facility	23,500			—			23,500
Canton Bonds	9,520			373			9,147
Capital lease obligations	6,028			—			6,028
NG Advantage debt	13,068			237			12,831
Other debt	1,782			—			1,782
Total debt and capital lease obligations	314,348			1,972			312,376
Less amounts due within one year	(6,126		)	(183		)	(5,943		)
Total long-term debt and capital lease obligations	$	308,222		$	1,789		$	306,433



	September 30, 2017
	Principal Balances			Unamortized Debt Financing Costs			Balance Net of Financing Costs
7.5% Notes (1)	$	125,000		$	155		$	124,845
5.25% Notes	110,450			609			109,841
Capital lease obligations	868			—			868
NG Advantage debt	18,070			236			17,834
Other debt	1,456			—			1,456
Total debt and capital lease obligations	255,844			1,000			254,844
Less amounts due within one year	(29,305		)	(58		)	(29,247		)
Total long-term debt and capital lease obligations	$	226,539		$	942		$	225,597

(1) Includes $65,000 and $40,000 in principal amount held by T. Boone Pickens ("Mr. Pickens"), as of December 31, 2016 and September 30, 2017, respectively, which is classified as “Long-term debt, related party” on the condensed consolidated balance sheet. See the description below for more information.

7.5% Notes

On July 11, 2011, the Company entered into a loan agreement (the “CHK Agreement”) with Chesapeake NG Ventures Corporation (“Chesapeake”), an indirect wholly owned subsidiary of Chesapeake Energy Corporation, whereby Chesapeake agreed to purchase from the Company up to $150,000 of debt securities pursuant to the issuance of three convertible promissory notes over a three-year period, each having a principal amount of $50,000 (each a “CHK Note” and collectively the “CHK Notes” and, together with the CHK Agreement and other transaction documents, the “CHK Loan Documents”). The first CHK Note was issued on July 11, 2011 and the second CHK Note was issued on July 10, 2012.

On June 14, 2013 (the “Transfer Date”), Mr. Pickens and Green Energy Investment Holdings, LLC ("GEIH"), an affiliate of Leonard Green & Partners, L.P. (collectively, the “Buyers”), and Chesapeake entered into a note purchase agreement (“Note Purchase Agreement”) pursuant to which Chesapeake sold the outstanding CHK Notes (the “Sale”) to the Buyers. Chesapeake assigned to the Buyers all of its right, title and interest under the CHK Loan Documents (the “Assignment”), and each Buyer severally assumed all of the obligations of Chesapeake under the CHK Loan Documents arising after the Sale and the Assignment including, without limitation, the obligation to advance an additional $50,000 to the Company in June 2013 (the “Assumption”). The Company also entered into the Note Purchase Agreement for the purpose of consenting to the Sale, the Assignment and the Assumption.

Contemporaneously with the execution of the Note Purchase Agreement, the Company entered into a loan agreement with each Buyer (collectively, the “Amended Agreements”). The Amended Agreements have the same terms as the CHK Agreement, other than changes to reflect the new holders of the CHK Notes. Immediately following execution of the Amended Agreements, the Buyers delivered $50,000 to the Company in satisfaction of the funding requirement they had assumed from Chesapeake (the “2013 Advance”). In addition, the Company canceled the existing CHK Notes and issued replacement notes, and the Company also issued notes to the Buyers in exchange for the 2013 Advance (the replacement notes and the notes issued in exchange for the 2013 Advance are referred to herein as the “7.5% Notes”).

The 7.5% Notes have the same terms as the original CHK Notes, other than changes to reflect their different holders. They bear interest at the rate of 7.5% per annum and are convertible at the option of the holder into shares of the Company’s common stock at a conversion price of $15.80 per share (the “7.5% Notes Conversion Price”). Upon written notice to the Company, each holder of a 7.5% Note has the right to exchange all or any portion of the principal and accrued and unpaid interest under its 7.5% Notes for shares of the Company’s common stock at the 7.5% Notes Conversion Price.

Additionally, subject to certain restrictions, the Company can force conversion of each 7.5% Note into shares of its common stock if, following the second anniversary of the issuance date of a 7.5% Note, such shares trade at a 40% premium to the 7.5% Notes Conversion Price for at least 20 trading days in any consecutive 30 trading day period.

The entire principal balance of each 7.5% Note is due and payable seven years following its issuance and the Company may repay each 7.5% Note at maturity in shares of its common stock (with a value determined by the per share volume weighted-average price for the 20 trading days prior to the maturity date) or cash. All of the shares issuable upon conversion of the 7.5% Notes have been registered for resale by their holders pursuant to a registration statement that has been filed with and declared effective by the Securities and Exchange Commission.

The Amended Agreements provide for customary events of default which, if any of them occurs, would permit or require the principal of, and accrued interest on, the 7.5% Notes to become, or to be declared, due and payable. No events of default under the 7.5% Notes had occurred as of September 30, 2017.

On August 27, 2013, GEIH transferred $5,000 in principal amount of its 7.5% Notes to certain third parties.

On February 9, 2017, the Company purchased from Mr. Pickens, his 7.5% Note due July 2018 having an outstanding principal amount of $25,000 held by Mr. Pickens for a cash purchase price of $21,750. The Company's repurchase of this 7.5% Note resulted in a total gain of $3,191 for the three and nine months ended September 30, 2017.

On February 21, 2017, GEIH transferred an additional $11,800 in principal amount of its 7.5% Notes to a third party.

As a result of the foregoing transactions, as of September 30, 2017, (i) Mr. Pickens held 7.5% Notes in the aggregate principal amount of $40,000, (ii) GEIH held 7.5% Notes in the aggregate principal amount of $68,200, and (iii) other third parties held 7.5% Notes in the aggregate principal amount of $16,800.

5.25% Notes

In September 2013, the Company completed a private offering of $250,000 in principal amount of 5.25% Convertible Senior Notes due 2018 (the “5.25% Notes”) and entered into an indenture governing the 5.25% Notes (the “Indenture”).

The net proceeds from the sale of the 5.25% Notes after the payment of certain debt issuance costs of $7,805 were $242,195. The Company has used the net proceeds from the sale of the 5.25% Notes to fund capital expenditures and for general corporate purposes. The 5.25% Notes bear interest at a rate of 5.25% per annum, payable semi-annually in arrears on October 1 and April 1 of each year, beginning on April 1, 2014. The 5.25% Notes will mature on October 1, 2018, unless purchased, redeemed or converted prior to such date in accordance with their terms and the terms of the Indenture.

Holders may convert their 5.25% Notes, at their option, at any time prior to the close of business on the business day immediately preceding the maturity date of the 5.25% Notes. Upon conversion, the Company will deliver a number of shares of its common stock, per $1 principal amount of 5.25% Notes, equal to the conversion rate then in effect (together with a cash payment in lieu of any fractional shares). The initial conversion rate for the 5.25% Notes is 64.1026 shares of the Company’s common stock per $1 principal amount of 5.25% Notes (which is equivalent to an initial conversion price of approximately $15.60 per share of the Company’s common stock). The conversion rate is subject to adjustment upon the occurrence of certain specified events as described in the Indenture. Upon the occurrence of certain corporate events prior to the maturity date of the 5.25% Notes, the Company will, in certain circumstances, in addition to delivering the number of shares of the Company’s common stock deliverable upon conversion of the 5.25% Notes based on the conversion rate then in effect (together with a cash payment in lieu of any fractional shares), pay holders that convert their 5.25% Notes a cash make-whole payment in an amount as described in the Indenture. The Company may, at its option, irrevocably elect to settle its obligation to pay any such make-whole payment in shares of its common stock instead of in cash.

The amount of any make-whole payment, whether it is settled in cash or in shares of the Company’s common stock upon the Company’s election, will be determined based on the date on which the corporate event occurs or becomes effective and the stock price paid (or deemed to be paid) per share of the Company’s common stock in the corporate event, as described in the Indenture.

The Company may not redeem the 5.25% Notes prior to October 5, 2016. On or after October 5, 2016, the Company may, at its option, redeem for cash all or any portion of the 5.25% Notes if the closing sale price of the Company’s common stock for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading day period ending on, and including, the trading day immediately preceding the date on which notice of redemption is provided, exceeds 160% of the conversion price on each applicable trading day. In the event of the Company’s redemption of the 5.25% Notes, the redemption price will equal 100% of the principal amount of the 5.25% Notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date. No sinking fund is provided for in the 5.25% Notes.

If the Company undergoes a fundamental change (as defined in the Indenture) prior to the maturity date of the 5.25% Notes, subject to certain conditions as described in the Indenture, holders may require the Company to purchase, for cash, all or any portion of their 5.25% Notes at a repurchase price equal to 100% of the principal amount of the 5.25% Notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change purchase date.

The Indenture contains customary events of default with customary cure periods, including, without limitation, failure to make required payments or deliveries of shares of the Company’s common stock when due under the Indenture, failure to comply with certain covenants under the Indenture, failure to pay when due or acceleration of certain other indebtedness of the Company or certain of its subsidiaries, and certain events of bankruptcy and insolvency of the Company or certain of its subsidiaries. The occurrence of an event of default under the Indenture will allow either the trustee or the holders of at least 25% in principal amount of the then-outstanding 5.25% Notes to accelerate, or upon an event of default arising from certain events of bankruptcy or insolvency of the Company, will automatically cause the acceleration of, all amounts due under the 5.25% Notes. No events of default under the 5.25% Notes had occurred as of September 30, 2017.

The 5.25% Notes are senior unsecured obligations of the Company and rank senior in right of payment to the Company’s future indebtedness that is expressly subordinated in right of payment to the 5.25% Notes; equal in right of payment to the Company’s unsecured indebtedness that is not so subordinated; effectively junior to any of the Company’s secured indebtedness to the extent of the value of the assets securing such indebtedness; and structurally junior to all indebtedness (including trade payables) of the Company’s subsidiaries.

During the year ended December 31, 2016, the Company paid an aggregate of $84,344 in cash to repurchase and retire $114,550 in aggregate principal amount of the 5.25% Notes, together with $1,546 in accrued and unpaid interest thereon. Additionally, pursuant to a privately negotiated exchange agreement with certain holders of the 5.25% Notes, on May 4, 2016, the Company issued 6,265,829 shares of its common stock in exchange for an aggregate principal amount of $25,000 of 5.25% Notes held by such holders and accrued and unpaid interest thereon. The value of the shares of the Company's common stock issued to the holders of the 5.25% Notes in the exchange has been excluded from the Company's condensed consolidated statements of cash flows as it is a non-cash financing activity. The Company's repurchase and exchange of 5.25% Notes for the year ended December 31, 2016 resulted in a total gain of $35,239 recorded during the period. All repurchased and exchanged 5.25% Notes have been surrendered to the trustee for such notes and canceled in full and the Company has no further obligations under such notes.

Plains Credit Facility

On February 29, 2016, the Company entered into a Loan and Security Agreement (the “Plains LSA”) with PlainsCapital Bank (“Plains”), pursuant to which Plains agreed to lend the Company up to $50,000 on a revolving basis from time to time for a term of one year (the “Credit Facility”). All amounts advanced under the Credit Facility were due and payable on February 28, 2017. Simultaneously, the Company drew $50,000 under this Credit Facility, which the Company repaid in full on August 31, 2016. On October 31, 2016, the Plains LSA was amended solely to extend the Credit Facility's maturity date from February 28, 2017 to September 30, 2018. On December 22, 2016, the Company drew $23,500 under the Credit Facility, which the Company repaid in full on March 31, 2017. As a result, the Company had no amounts outstanding under the Credit Facility as of September 30, 2017.

The Credit Facility is evidenced by a promissory note the Company issued on February 29, 2016 in favor of Plains (the “Plains Note”). Interest on the Plains Note is payable monthly and accrues at a rate equal to the greater of (i) the then-current LIBOR rate plus 2.30% or (ii) 2.70%. As collateral security for the prompt payment in full when due of the Company's obligations to Plains under the Plains LSA and the Plains Note, the Company pledged to and granted Plains a security interest in all of its right, title and interest in the cash and corporate and municipal bonds rated AAA, AA or A by Standard & Poor’s Rating Services that the Company holds in an account at Plains. In connection with such pledge and security interest granted under the Credit Facility, on February 29, 2016, the Company entered into a Pledged Account Agreement with Plains and PlainsCapital Bank - Wealth Management and Trust (the “Pledge Agreement” and collectively with the Plains LSA and the Plains Note, the “Plains Loan Documents”).The Plains Loan Documents include certain covenants of the Company and also provide for customary events of default, which, if any of them occurs, would permit or require, among other things, the principal of, and accrued interest on, the Credit Facility to become, or to be declared, due and payable. Events of default under the Plains Loan Documents include, among others, the occurrence of certain bankruptcy events, the failure to make payments when due under the Plains Note and the transfer or disposal of the collateral under the Plains LSA. No events of default under the Plains Loan Documents had occurred as of September 30, 2017.

Canton Bonds

On March 19, 2014, Canton Renewables, LLC (“Canton”), a former subsidiary of the Company, completed the issuance of Solid Waste Facility Limited Obligation Revenue Bonds (Canton Renewables, LLC — Sauk Trail Hills Project) Series 2014 in the aggregate principal amount of $12,400 (the “Canton Bonds”).

The Canton Bonds were issued by the Michigan Strategic Fund (the “Issuer”) and the proceeds of such issuance were loaned by the Issuer to Canton pursuant to a loan agreement that became effective on March 19, 2014.

On March 31, 2017, Canton was sold to BP in the Asset Sale (see Note 3). As a result, the Canton Bonds became the obligation of BP as of such date.

NG Advantage Debt

On May 12, 2016 and January 24, 2017, respectively, NG Advantage entered into a Loan and Security Agreement (the “Commerce LSA”) with Commerce Bank & Trust Company (“Commerce”), pursuant to which Commerce agreed to lend NG Advantage $6,300 and $6,150, respectively. The proceeds were primarily used to fund the purchases of CNG trailers and equipment. Interest and principal for both loans are payable monthly in 84 equal monthly installments at an annual rate of 4.41% and 5.0%, respectively. As collateral security for the prompt payment in full when due of NG Advantage's obligations to Commerce under the Commerce LSA, NG Advantage pledged to and granted Commerce a security interest in all of its right, title and interest in the CNG trailers and equipment purchased with the proceeds received under the Commerce LSA.

On November 30, 2016, NG Advantage entered into a Loan and Security Agreement (the "Wintrust LSA") with Wintrust Commercial Finance (“Wintrust”), pursuant to which Wintrust agreed to lend NG Advantage $4,695. The proceeds were primarily used to fund the purchases of CNG trailers and equipment. Interest and principal is payable monthly in 72 equal monthly installments at an annual rate of 5.17%. As collateral security for the prompt payment in full when due of NG Advantage's obligations to Wintrust under the Wintrust LSA, NG Advantage pledged to and granted Wintrust a security interest in all of its right, title and interest in the CNG trailers and equipment purchased with the proceeds received under the Wintrust LSA.

NG Advantage has other debt for trailers and equipment due at various dates through 2021 bearing interest at rates up to 6.01%, with weighted -average interest rates of 5.51% and 5.56%, and outstanding principal balance of $2,598 and $3,222 as of December 31, 2016 and September 30, 2017, respectively.

Other Debt

The Company has other debt due at various dates through 2023 bearing interest at rates up to 19.69% with weighted -average interest rates of 5.72% and 6.35% as of December 31, 2016 and September 30, 2017, respectively.

Net Loss Per Share

9 Months Ended

Sep. 30, 2017

Earnings Per Share [Abstract]

Net Loss Per Share

Basic net loss per share is computed by dividing the net loss attributable to Clean Energy Fuels Corp. by the weighted-average number of common shares outstanding and common shares issuable for little or no cash consideration during the period. Diluted net loss per share is computed by dividing the net loss attributable to Clean Energy Fuels Corp. by the weighted-average number of common shares outstanding and common shares issuable for little or no cash consideration during the period and potentially dilutive securities outstanding during the period, and therefore reflects the dilution from common shares that may be issued upon exercise or conversion of these potentially dilutive securities, such as stock options, warrants, convertible notes and restricted stock units. The dilutive effect of stock awards and warrants is computed under the treasury stock method. The dilutive effect of convertible notes and restricted stock units is computed under the if-converted method. Potentially dilutive securities are excluded from the computations of diluted net loss per share if their effect would be antidilutive.

The information required to compute basic and diluted net loss per share is as follows:



	Three Months Ended September 30,		Nine Months Ended September 30,
	2016	2017	2016	2017
Weighted-average common shares outstanding	130,436,038	150,927,825	112,819,041	150,128,204

The following potentially dilutive securities have been excluded from the diluted net loss per share calculations because their effect would have been antidilutive. Although such securities were antidilutive for the respective periods, they could be dilutive in the future.



	Three Months Ended September 30,		Nine Months Ended September 30,
	2016	2017	2016	2017
Stock Options	11,582,091	9,648,613	11,582,091	9,648,613
Convertible Notes	21,006,491	14,991,521	21,006,491	14,991,521
Restricted Stock Units	2,432,930	2,403,266	2,432,930	2,403,266
Total	35,021,512	27,043,400	35,021,512	27,043,400

At-The-Market Offering Program

On May 31, 2017, the Company terminated its equity distribution agreement (the “Sales Agreement”) with Citigroup Global Markets Inc. (“Citigroup”), as sales agent and/or principal. The Sales Agreement was terminable at will upon written notification by the Company with no penalty. Pursuant to the Sales Agreement, the Company was entitled to issue and sell, from time to time, through or to Citigroup, shares of its common stock having an aggregate offering price of up to $200,000 in an “at-the-market” offering program (the “ATM Program”). The ATM Program commenced on November 11, 2015 when the Company and Citigroup entered into the original equity distribution agreement, which was amended and restated on September 9, 2016 and again on December 21, 2016 prior to its termination.

The following table summarizes the activity under the ATM Program for the periods presented:



	Three Months Ended September 30,		Three Months Ended September 30,		Nine Months Ended September 30,		Nine Months Ended September 30,
(in 000s, except per-share amounts)	2016		2017		2016		2017
Gross proceeds	$	16,066	$	—	$	69,113	$	10,767
Fees and issuance costs	386		—		1,728		311
Net proceeds	$	15,680	$	—	$	67,385	$	10,456
Shares issued	3,824,144		—		21,325,587		3,802,500

Stock-Based Compensation

9 Months Ended

Sep. 30, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

The following table summarizes the compensation expense and related income tax benefit related to the Company's stock-based compensation arrangements recognized in the condensed consolidated statements of operations during the periods:



	Three Months Ended September 30,				Nine Months Ended September 30,
	2016		2017		2016		2017
Stock-based compensation expense, net of $0 tax in 2016 and 2017 (1)	$	2,077	$	2,216	$	6,533	$	6,904

(1) $300 of stock-based compensation expense for the three and nine months ended September 30, 2017 is recorded in asset impairments and other charges in the condensed consolidated statements of operations and is reported in non-cash portion of asset impairments and other charges in the condensed consolidated statements of cash flows. See Note 2 for more information.

At September 30, 2017, there was $7,194 of total unrecognized compensation costs related to non-vested shares subject to outstanding stock options and restricted stock units, which is expected to be expensed over a weighted-average period of approximately 1.60 years.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References + Details

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company’s income tax benefit (expense) was $(416) and $44 for the three months ended September 30, 2016 and 2017, respectively, and $(1,229) and $2,183 for the nine months ended September 30, 2016 and 2017, respectively. Tax benefit (expense) for all periods was comprised of taxes due on the Company’s U.S. and foreign operations. The increase in the Company’s income tax benefit for the three months ended September 30, 2017 as compared to the three months ended September 30, 2016 was primarily due to a decrease in the deferred tax expense attributed to the reduction of goodwill amortization following the Asset Sale (see Note 3). The increase in the Company's income tax benefit for the nine months ended September 30, 2017 as compared to the nine months ended September 30, 2016 was primarily due to a deferred tax benefit from the Asset Sale. The effective tax rates for the three and nine months ended September 30, 2016 and 2017 are different from the federal statutory tax rate primarily as a result of losses for which no tax benefit has been recognized. Following the Asset Sale, the Company also benefited from the utilization of federal and state net operating loss ("NOL") carryovers that offset all of the Company's federal and the majority of its state taxes. In addition to the decrease in its deferred tax liability of $2,493 attributed to the reduction in goodwill following the Asset Sale, the utilization of NOLs also resulted in a decrease of $29,768 in the Company's deferred tax assets attributed to NOLs and a corresponding decrease in the Company's deferred tax asset valuation allowance. The Company did not record a change in its liability for unrecognized tax benefits or penalties in the three and nine months ended September 30, 2016 or 2017. The net interest incurred was immaterial for both the three and nine months ended September 30, 2016 and 2017, respectively.

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Environmental Matters The Company is subject to federal, state, local and foreign environmental laws and regulations. The Company does not anticipate any expenditures to comply with such laws and regulations that would have a material impact on the Company's consolidated financial position, results of operations or liquidity. The Company believes that its operations comply, in all material respects, with applicable federal, state, local and foreign environmental laws and regulations. Litigation, Claims and Contingencies The Company may become party to various legal actions that arise in the ordinary course of its business. The Company is also subject to audit by tax and other authorities for varying periods in various federal, state, local and foreign jurisdictions, and disputes may arise during the course of these audits. It is impossible to determine the ultimate liabilities that the Company may incur resulting from any of these lawsuits, claims, proceedings, audits, commitments, contingencies and related matters or the timing of these liabilities, if any. If these matters were to ultimately be resolved unfavorably, it is possible that such an outcome could have a material adverse effect upon the Company’s consolidated financial position, results of operations, or liquidity. The Company, does not, however, anticipate such an outcome and it believes the ultimate resolution of these matters will not have a material adverse effect on the Company’s consolidated financial position, results of operations, or liquidity.

Alternative Fuels Excise Tax Credit	9 Months Ended
Alternative Fuels Excise Tax Credit	Sep. 30, 2017
Alternative Fuels Excise Tax Credit
Alternative Fuels Excise Tax Credit	Alternative Fuels Excise Tax Credit In December 2015, the U.S. Congress passed the Consolidated Appropriations Act, which included an alternative fuels tax credit referred to in these condensed consolidated financial statements as "VETC." The credit was made retroactive to January 1, 2015 and extended through December 31, 2016, except that the alternative fuels tax credit for LNG sold as a vehicle fuel in 2016 was based on the diesel gallon equivalent of LNG sold, rather than the liquid gallon of LNG sold as it was in 2015. As a result, the Company was eligible to receive a credit of $0.50 per gasoline gallon equivalent of CNG sold as a vehicle fuel in 2016 and $0.50 per diesel gallon equivalent of LNG sold as a vehicle fuel in 2016. Based on the service relationship with its customers, either the Company or its customers claimed the credit. The Company records its VETC credits, if any, as revenue in its condensed consolidated statements of operations because the credits are fully payable and do not need to offset income tax liabilities to be received. As such, the credits are not deemed income tax credits under the accounting guidance applicable to income taxes. VETC revenue for the three and nine months ended September 30, 2016 was $6,693 and $19,609, respectively. VETC ceased to be available after it expired on December 31, 2016 and may not be available for any subsequent period.

Recently Issued and Adopted Accounting Standards	9 Months Ended
Recently Issued and Adopted Accounting Standards	Sep. 30, 2017
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recently Issued Accounting Standards	Recently Issued and Adopted Accounting Standards In May 2017, the FASB issued Accounting Standards Update (“ASU”) 2017-09, Compensation - Stock Compensation (Topic 718): Scope Modification Accounting. This ASU allows entities to make certain changes to awards without accounting for them as modifications. It does not change the accounting for modifications. Specifically, an entity will not apply modification accounting if all of the following are the same immediately before and after the change: (1) the award's fair value (or calculated value or intrinsic value if those measurement methods are used), (2) the award's vesting conditions, and (3) the award's classification as an equity or liability instrument. The new standard is effective for fiscal years beginning after December 15, 2017, which for the Company is the first quarter of 2018. The Company does not expect the adoption of the guidance to have a material impact on its consolidated financial statements. In January 2017, the FASB issued ASU 2017-03, Accounting Changes and Error Corrections (Topic 250) and Investments - Equity Method and Joint Ventures (Topic 323): Amendments to SEC Paragraphs Pursuant to Staff Announcements at the September 22, 2016 and November 17, 2016 EITF Meetings. This ASU requires registrants to disclose the effect that ASU 2014-09 (Revenue from Contracts with Customers (Topic 606), ASU 2016-02 (Leases (Topic 842), and ASU 2016-13 (Financial Instruments--Credit Losses (Topic 326) will have on their financial statements when adopted in a future period. In cases where a registrant cannot reasonably estimate the impact of the adoption, additional qualitative disclosures should be considered to assist the reader in assessing the significance of the standard’s impact on its financial statements. This guidance was effective upon issuance and other than enhancements to the qualitative disclosures regarding the future adoption of the referenced ASUs above, adoption of this ASU is not expected to have any impact on the Company’s consolidated financial statements and related disclosures. In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory. Under the new standard, the selling (transferring) entity is required to recognize a current tax expense or benefit upon transfer of the asset. Similarly, the purchasing (receiving) entity is required to recognize a deferred tax asset or liability, as well as the related deferred tax benefit or expense, upon purchase or receipt of the asset. The Company early adopted the standard as of January 1, 2017. This election was implemented under the modified retrospective approach, resulting in a $302 increase in accumulated deficit representing the cumulative recognition of the income tax consequences of intra-entity transfers of assets other than inventory that occurred before the adoption date. In March 2016, the FASB issued ASU No. 2016-09, Compensation – Stock Compensation (Topic 718): Improvements to Employee Share-Based Payments Accounting. The new standard was issued to simplify the accounting for share-based payment transactions, including income tax consequences, the classification of awards as either equity or liabilities, and the classification on the statement of cash flows. The Company adopted the standard as of January 1, 2017 and in connection with the adoption, the Company elected to recognize forfeitures when they occur. Previously, the Company estimated a forfeiture rate in accordance with prior guidance. This election was implemented under the modified retrospective approach with a cumulative effect of an increase in accumulated deficit of $194, net of tax. This adjustment represents the cumulative additional compensation expense that would have been amortized through the date of adoption had this accounting policy election been in place. This ASU also eliminates the requirement to defer recognition of an excess tax benefit until the benefit is realized through a reduction to taxes payable. As a result, the Company’s deferred tax asset relating to its net operating loss carryovers increased by $8,600 with a corresponding increase in the deferred tax asset valuation allowance. The Company also adopted, on a prospective basis, (1) the classification of excess tax benefits as an operating activity in the condensed consolidated statements of cash flows and (2) the exclusion of the amount of excess tax benefits when applying the treasury stock method for the Company’s diluted loss per share calculation. Neither of these adoptions had a material impact on the Company's cash flows or diluted loss per share calculation for the nine months ended September 30, 2017. Additionally, the Company continues to (1) classify cash paid by the Company for directly withholding shares for tax withholding purposes as a financing activity in the condensed consolidated statements of cash flows and (2) withhold the statutory minimum taxes for participants in the Company’s stock-based compensation plans. In May 2014, the FASB issued ASU 2014-09 related to revenue from contracts with customers, which, along with amendments issued in 2015, 2016, and 2017 will provide a single, comprehensive revenue recognition model for all contracts with customers. The underlying principle is to recognize revenue when promised goods or services are transferred to customers in amounts that reflect the consideration that is expected to be received for those goods or services. The new standard also requires entities to enhance disclosures about the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. This ASU, as amended, will be effective for annual reporting periods after December 15, 2017, which for the Company is the first quarter of 2018. The new revenue standard may be applied retrospectively to each prior period presented or retrospectively with the cumulative effect recognized in retained earnings as of the date of adoption ("modified retrospective basis"). The Company expects to adopt this ASU on a modified retrospective basis and is currently evaluating the impact of this ASU on its consolidated financial statements and related disclosures. While the Company has not yet identified any material changes in the timing of revenue recognition for our various revenues streams, our evaluation is ongoing and not complete.

- Definition

The entire disclosure of changes in accounting principles, including adoption of new accounting pronouncements, that describes the new methods, amount and effects on financial statement line items.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Change in Accounting Principle
-URI http://asc.fasb.org/extlink&oid=6507316

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Direct Effects of a Change in Accounting Principle
-URI http://asc.fasb.org/extlink&oid=66092750

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 3
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6515603

Reference 5: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Name Accounting Standards Codification
-Topic 270
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.10-01.(b)(6))
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-Name Accounting Standards Codification
-Topic 250
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Glossary Retrospective Application
-URI http://asc.fasb.org/extlink&oid=6523989

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-Name Accounting Standards Codification
-Topic 270
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+ Details

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 2017
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On October 23, 2017, the Company paid $5,486 to settle an obligation to deliver LCFS Credits to a third party. The Company took this action because it did not at that time have access to LCFS Credits it generates due to restrictions imposed on the Company's LCFS Credit account pending completion of an ongoing administrative review by the California Air Resources Board ("CARB"). If CARB's administrative review results in the retirement of any of the Company's LCFS Credits, such that the Company cannot recover any portion of its cash payment through sales of such credits, then the Company may be required to recognize a charge equal to the value of the portion of its cash payment that cannot be recovered.

General (Policies)	9 Months Ended
General (Policies)	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying interim unaudited condensed consolidated financial statements include the accounts of the Company and its subsidiaries, and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to state fairly the Company’s financial position, results of operations, comprehensive loss and cash flows as of and for the three and nine months ended September 30, 2016 and 2017. All intercompany accounts and transactions have been eliminated in consolidation. The three and nine month periods ended September 30, 2016 and 2017 are not necessarily indicative of the results to be expected for the year ending December 31, 2017 or for any other interim period or for any future year. Certain information and disclosures normally included in the notes to the financial statements have been condensed or omitted pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”), but the resultant disclosures contained herein are in accordance with accounting principles generally accepted in the United States of America (“US GAAP”) as they apply to interim reporting. The condensed consolidated financial statements should be read in conjunction with the consolidated financial statements as of and for the year ended December 31, 2016 that are included in the Company’s Annual Report on Form 10-K filed with the SEC on March 7, 2017.
Reclassifications	Reclassifications Certain prior period line items in the condensed consolidated statements of operations have been reclassified to conform to the classifications used to prepare the condensed consolidated financial statements for the period ended September 30, 2017.
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements in conformity with US GAAP requires management to make estimates and assumptions that affect the amounts reported in the accompanying unaudited condensed consolidated financial statements and these notes. Actual results could differ from those estimates and may result in material effects on the Company’s operating results and financial position.
Recently Issued Accounting Standards	Recently Issued and Adopted Accounting Standards In May 2017, the FASB issued Accounting Standards Update (“ASU”) 2017-09, Compensation - Stock Compensation (Topic 718): Scope Modification Accounting. This ASU allows entities to make certain changes to awards without accounting for them as modifications. It does not change the accounting for modifications. Specifically, an entity will not apply modification accounting if all of the following are the same immediately before and after the change: (1) the award's fair value (or calculated value or intrinsic value if those measurement methods are used), (2) the award's vesting conditions, and (3) the award's classification as an equity or liability instrument. The new standard is effective for fiscal years beginning after December 15, 2017, which for the Company is the first quarter of 2018. The Company does not expect the adoption of the guidance to have a material impact on its consolidated financial statements. In January 2017, the FASB issued ASU 2017-03, Accounting Changes and Error Corrections (Topic 250) and Investments - Equity Method and Joint Ventures (Topic 323): Amendments to SEC Paragraphs Pursuant to Staff Announcements at the September 22, 2016 and November 17, 2016 EITF Meetings. This ASU requires registrants to disclose the effect that ASU 2014-09 (Revenue from Contracts with Customers (Topic 606), ASU 2016-02 (Leases (Topic 842), and ASU 2016-13 (Financial Instruments--Credit Losses (Topic 326) will have on their financial statements when adopted in a future period. In cases where a registrant cannot reasonably estimate the impact of the adoption, additional qualitative disclosures should be considered to assist the reader in assessing the significance of the standard’s impact on its financial statements. This guidance was effective upon issuance and other than enhancements to the qualitative disclosures regarding the future adoption of the referenced ASUs above, adoption of this ASU is not expected to have any impact on the Company’s consolidated financial statements and related disclosures. In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory. Under the new standard, the selling (transferring) entity is required to recognize a current tax expense or benefit upon transfer of the asset. Similarly, the purchasing (receiving) entity is required to recognize a deferred tax asset or liability, as well as the related deferred tax benefit or expense, upon purchase or receipt of the asset. The Company early adopted the standard as of January 1, 2017. This election was implemented under the modified retrospective approach, resulting in a $302 increase in accumulated deficit representing the cumulative recognition of the income tax consequences of intra-entity transfers of assets other than inventory that occurred before the adoption date. In March 2016, the FASB issued ASU No. 2016-09, Compensation – Stock Compensation (Topic 718): Improvements to Employee Share-Based Payments Accounting. The new standard was issued to simplify the accounting for share-based payment transactions, including income tax consequences, the classification of awards as either equity or liabilities, and the classification on the statement of cash flows. The Company adopted the standard as of January 1, 2017 and in connection with the adoption, the Company elected to recognize forfeitures when they occur. Previously, the Company estimated a forfeiture rate in accordance with prior guidance. This election was implemented under the modified retrospective approach with a cumulative effect of an increase in accumulated deficit of $194, net of tax. This adjustment represents the cumulative additional compensation expense that would have been amortized through the date of adoption had this accounting policy election been in place. This ASU also eliminates the requirement to defer recognition of an excess tax benefit until the benefit is realized through a reduction to taxes payable. As a result, the Company’s deferred tax asset relating to its net operating loss carryovers increased by $8,600 with a corresponding increase in the deferred tax asset valuation allowance. The Company also adopted, on a prospective basis, (1) the classification of excess tax benefits as an operating activity in the condensed consolidated statements of cash flows and (2) the exclusion of the amount of excess tax benefits when applying the treasury stock method for the Company’s diluted loss per share calculation. Neither of these adoptions had a material impact on the Company's cash flows or diluted loss per share calculation for the nine months ended September 30, 2017. Additionally, the Company continues to (1) classify cash paid by the Company for directly withholding shares for tax withholding purposes as a financing activity in the condensed consolidated statements of cash flows and (2) withhold the statutory minimum taxes for participants in the Company’s stock-based compensation plans. In May 2014, the FASB issued ASU 2014-09 related to revenue from contracts with customers, which, along with amendments issued in 2015, 2016, and 2017 will provide a single, comprehensive revenue recognition model for all contracts with customers. The underlying principle is to recognize revenue when promised goods or services are transferred to customers in amounts that reflect the consideration that is expected to be received for those goods or services. The new standard also requires entities to enhance disclosures about the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. This ASU, as amended, will be effective for annual reporting periods after December 15, 2017, which for the Company is the first quarter of 2018. The new revenue standard may be applied retrospectively to each prior period presented or retrospectively with the cumulative effect recognized in retained earnings as of the date of adoption ("modified retrospective basis"). The Company expects to adopt this ASU on a modified retrospective basis and is currently evaluating the impact of this ASU on its consolidated financial statements and related disclosures. While the Company has not yet identified any material changes in the timing of revenue recognition for our various revenues streams, our evaluation is ongoing and not complete.

Asset Impairments, Other Charges, and Inventory Valuation Provision (Tables)

9 Months Ended

Sep. 30, 2017

Restructuring and Related Activities [Abstract]

Restructuring and impairment charges

The following table summarizes these charges:



	Three and Nine Months Ended September 30, 2017
Workforce reduction and related charges	$	3,057
CECC asset impairments	32,274
Station closures and related charges	25,335
Total asset impairments and other charges	$	60,666
Inventory valuation provision	13,158
Total charges	$	73,824

The following table summarizes the total charges that will be settled with cash payments and their related liability balances as of September 30, 2017:



	Charges		Cash Payments Made in the Three Months Ended September 30, 2017			Balance as of September 30, 2017
Employee severance	$	2,757	$	(2,547	)	$	210
Lease termination fees and AROs for station closures	3,861		—			3,861
	$	6,618				$	4,071

Schedule of finite-lived intangible assets



	December 31, 2016		September 30, 2017		Remaining Useful Life (Years)
Technology	$	29,060	$	3,151	13
Customer relationships	2,239		117		1
Trademark and trade names	1,842		201		3
Total	$	33,141	$	3,469

Restricted Cash (Tables)

9 Months Ended

Sep. 30, 2017

Restricted Cash and Investments, Current [Abstract]

Schedule of components of restricted cash

Short-term restricted cash at December 31, 2016 and September 30, 2017 consisted of the following:



	December 31, 2016		September 30, 2017
Short-term restricted cash:
Standby letters of credit	$	1,753	$	1,463
Canton Bonds (see Note 13)	3,665		—
Held in escrow	1,578		—
Total short-term restricted cash	$	6,996	$	1,463

Investments (Tables)

9 Months Ended

Sep. 30, 2017

Investments, Debt and Equity Securities [Abstract]

Summary of short-term investments

Short-term investments as of December 31, 2016 consisted of the following:



	Amortized Cost		Gross Unrealized Losses			Estimated Fair Value
Municipal bonds and notes	$	8,791	$	(4	)	$	8,787
Corporate bonds	21,517		(7		)	21,510
Certificate of deposits	43,421		—			43,421
Total short-term investments	$	73,729	$	(11	)	$	73,718

Short-term investments as of September 30, 2017 consisted of the following:



	Amortized Cost		Gross Unrealized Losses			Estimated Fair Value
Municipal bonds and notes	$	21,470	$	(73	)	$	21,397
Zero coupon bonds	69,192		(59		)	69,133
Corporate bonds	39,596		(13		)	39,583
Certificate of deposits	21,408		—			21,408
Total short-term investments	$	151,666	$	(145	)	$	151,521

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2017

Fair Value Disclosures [Abstract]

Schedule of information by level for assets and liabilities that are measured at fair value on a recurring basis

The following tables provide information by level for assets and liabilities that are measured at fair value on a recurring basis as of December 31, 2016 and September 30, 2017, respectively:



Description	Balance at December 31, 2016		Level 1		Level 2		Level 3
Assets:
Available-for-sale securities(1):
Municipal bonds and notes	$	8,787	$	—	$	8,787	$	—
Corporate bonds	21,510		—		21,510		—
Certificate of deposits	43,421		—		43,421		—
Liabilities:
Warrants(2)	581		—		—		581



Description	Balance at September 30, 2017		Level 1		Level 2		Level 3
Assets:
Available-for-sale securities(1):
Municipal bonds and notes	$	21,397	$	—	$	21,397	$	—
Zero coupon bonds	69,133		—		69,133		—
Corporate bonds	39,583		—		39,583		—
Certificate of deposits	21,408		—		21,408		—
Liabilities:
Warrants(2)	543		—		—		543

(1) Included in short-term investments in the condensed consolidated balance sheets. See Note 6 for more information.

(2) Included in accrued liabilities and other long-term liabilities in the condensed consolidated balance sheets.

Other Receivables (Tables)

9 Months Ended

Sep. 30, 2017

Receivables [Abstract]

Schedule of other receivables

Other receivables as of December 31, 2016 and September 30, 2017 consisted of the following:



	December 31, 2016		September 30, 2017
Loans to customers to finance vehicle purchases	$	7,416	$	6,896
Accrued customer billings	4,308		6,328
Fuel tax credits	6,358		—
Other	3,852		3,029
Total other receivables	$	21,934	$	16,253

Inventory (Tables)

9 Months Ended

Sep. 30, 2017

Inventory Disclosure [Abstract]

Schedule of inventories

Inventories as of December 31, 2016 and September 30, 2017 consisted of the following:



	December 31, 2016		September 30, 2017
Raw materials and spare parts (1)	$	24,843	$	42,487
Work in process	845		806
Finished goods	3,856		1,331
Total inventories	$	29,544	$	44,624


(1)	As of September 30, 2017, this amount also includes $19,394 for certain station parts which historically were classified as construction in progress within Land, property, and equipment, net, that are now reported in Inventory in the condensed consolidated balance sheets because they will primarily be used for stations to be sold. See Note 2 for more information.

Land, Property and Equipment (Tables)

9 Months Ended

Sep. 30, 2017

Property, Plant and Equipment [Abstract]

Summary of land, property and equipment

Land, property and equipment as of December 31, 2016 and September 30, 2017 consisted of the following:



	December 31, 2016			September 30, 2017
Land	$	2,858		$	2,858
LNG liquefaction plants	94,634			94,633
RNG plants (1)	47,545			—
Station equipment (2)	341,605			298,681
Trailers	54,985			59,312
Other equipment (2)	93,118			94,389
Construction in progress (2) (3)	117,662			79,366
	752,407			629,239
Less: accumulated depreciation	(268,484		)	(265,466		)
Total land, property and equipment, net	$	483,923		$	363,773

(1) The RNG plants were sold in the Asset Sale (see Note 3 for more information).


(2)	Certain of these assets were written down during the three months ended September 30, 2017 (see Note 2 for more information).


(3)	As of September 30, 2017, $19,394 of certain station parts which historically were classified as construction in progress within Land, property, and equipment, net, that are now reported in Inventory in the condensed consolidated balance sheets because they will primarily be used for stations to be sold.

Accrued Liabilities (Tables)

9 Months Ended

Sep. 30, 2017

Payables and Accruals [Abstract]

Schedule of accrued liabilities

Accrued liabilities as of December 31, 2016 and September 30, 2017 consisted of the following:



	December 31, 2016		September 30, 2017
Accrued alternative fuels incentives (1)	$	9,840	$	2,270
Accrued employee benefits	4,317		3,999
Accrued interest	1,849		39
Accrued gas and equipment purchases	11,657		10,220
Accrued property and other taxes	4,572		4,164
Salaries and wages (2)	12,293		8,636
Other (3)	8,073		12,662
Total accrued liabilities	$	52,601	$	41,990


(1)	Includes the amount of RINs and LCFS Credits and, as of December 31, 2016, the amount of a federal alternative fuels tax credit ("VETC") payable to third parties. VETC expired as of December 31, 2016, and as a result, no VETC amounts were accrued as of September 30, 2017 (see Note 18 for more information about VETC).


(2)	The amount as of September 30, 2017 includes severance accruals related to a workforce reduction during the three months ended September 30, 2017 (see Note 2 for more information).


(3)	The amount as of September 30, 2017 also includes lease termination fees and AROs related to closure of certain fueling stations (see Note 2 for more information).

Debt (Tables)

9 Months Ended

Sep. 30, 2017

Debt Disclosure [Abstract]

Schedule of debt and capital lease obligations

Debt and capital lease obligations as of December 31, 2016 and September 30, 2017 consisted of the following and are further discussed below:



	December 31, 2016
	Principal Balances			Unamortized Debt Financing Costs			Balance, Net of Financing Costs
7.5% Notes (1)	$	150,000		$	274		$	149,726
5.25% Notes	110,450			1,088			109,362
Plains Credit Facility	23,500			—			23,500
Canton Bonds	9,520			373			9,147
Capital lease obligations	6,028			—			6,028
NG Advantage debt	13,068			237			12,831
Other debt	1,782			—			1,782
Total debt and capital lease obligations	314,348			1,972			312,376
Less amounts due within one year	(6,126		)	(183		)	(5,943		)
Total long-term debt and capital lease obligations	$	308,222		$	1,789		$	306,433



	September 30, 2017
	Principal Balances			Unamortized Debt Financing Costs			Balance Net of Financing Costs
7.5% Notes (1)	$	125,000		$	155		$	124,845
5.25% Notes	110,450			609			109,841
Capital lease obligations	868			—			868
NG Advantage debt	18,070			236			17,834
Other debt	1,456			—			1,456
Total debt and capital lease obligations	255,844			1,000			254,844
Less amounts due within one year	(29,305		)	(58		)	(29,247		)
Total long-term debt and capital lease obligations	$	226,539		$	942		$	225,597

Net Loss Per Share (Tables)

9 Months Ended

Sep. 30, 2017

Earnings Per Share [Abstract]

Schedule of information required to compute basic and diluted net loss per share

The information required to compute basic and diluted net loss per share is as follows:



	Three Months Ended September 30,		Nine Months Ended September 30,
	2016	2017	2016	2017
Weighted-average common shares outstanding	130,436,038	150,927,825	112,819,041	150,128,204

Schedule of potentially dilutive securities that have been excluded from the diluted net loss per share calculations because their effect would have been antidilutive



	Three Months Ended September 30,		Nine Months Ended September 30,
	2016	2017	2016	2017
Stock Options	11,582,091	9,648,613	11,582,091	9,648,613
Convertible Notes	21,006,491	14,991,521	21,006,491	14,991,521
Restricted Stock Units	2,432,930	2,403,266	2,432,930	2,403,266
Total	35,021,512	27,043,400	35,021,512	27,043,400

Schedule of at-the-market offering program activity

The following table summarizes the activity under the ATM Program for the periods presented:



	Three Months Ended September 30,		Three Months Ended September 30,		Nine Months Ended September 30,		Nine Months Ended September 30,
(in 000s, except per-share amounts)	2016		2017		2016		2017
Gross proceeds	$	16,066	$	—	$	69,113	$	10,767
Fees and issuance costs	386		—		1,728		311
Net proceeds	$	15,680	$	—	$	67,385	$	10,456
Shares issued	3,824,144		—		21,325,587		3,802,500

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of compensation expense and related income tax benefit related to the stock-based compensation expense recognized



	Three Months Ended September 30,				Nine Months Ended September 30,
	2016		2017		2016		2017
Stock-based compensation expense, net of $0 tax in 2016 and 2017 (1)	$	2,077	$	2,216	$	6,533	$	6,904

Asset Impairments, Other Charges, and Inventory Valuation Provision (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) station	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) station	Sep. 30, 2016 USD ($)	Sep. 29, 2017 USD ($)
Restructuring Cost and Reserve [Line Items]
Asset impairments and other charges	$ 60,666	$ 0	$ 60,666	$ 0
Inventory valuation provision	13,158	$ 0	13,158	$ 0
Severance costs	3,057		3,057
Discontinued Operations, Held-for-sale or Disposed of by Sale \| Station Closures
Restructuring Cost and Reserve [Line Items]
Inventory held-for-sale	27,198		27,198
Fair Value, Measurements, Nonrecurring \| Level 3
Restructuring Cost and Reserve [Line Items]
Asset impairments and other charges	52,658
Impaired long-lived assets	6,709		6,709		$ 59,367
Employee Severance
Restructuring Cost and Reserve [Line Items]
Severance costs			2,757
Share-based compensation expense			300
Facility Closing
Restructuring Cost and Reserve [Line Items]
Inventory valuation provision			7,804
Impairment of intangible assets			32,274
Other restructuring charges	$ 4,951
Strategic shift in operations
Restructuring Cost and Reserve [Line Items]
Inventory valuation provision			$ 5,354
Natural Gas Fueling Stations \| Facility Closing
Restructuring Cost and Reserve [Line Items]
Number of expected natural gas fueling station closures \| station	42		42
Natural Gas Fueling Stations \| Facility Closing \| Fair Value, Measurements, Nonrecurring \| Level 3
Restructuring Cost and Reserve [Line Items]
Asset impairments and other charges	$ 20,384		$ 52,658
Impaired long-lived assets	$ 2,886		$ 2,886		$ 23,270

Asset Impairments, Other Charges, and Inventory Valuation Provision - Summary of Charges (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Restructuring and Related Activities [Abstract]
Workforce reduction and related charges	$ 3,057		$ 3,057
CECC asset impairments	32,274		32,274
Station closures and related charges	25,335		25,335
Total asset impairments and other charges	60,666	$ 0	60,666	$ 0
Inventory valuation provision	13,158	$ 0	13,158	$ 0
Total charges	$ 73,824		$ 73,824

Asset Impairments, Other Charges, and Inventory Valuation Provision - Intangible Assets (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 3,469	$ 33,141
Technology
Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 3,151	29,060
Remaining Useful Life	13 years
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 117	2,239
Remaining Useful Life	1 year
Trademark and trade names
Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 201	$ 1,842
Remaining Useful Life	3 years

Asset Impairments, Other Charges, and Inventory Valuation Provision - Cash Related Charges (Details) $ in Thousands	3 Months Ended
	Sep. 30, 2017 USD ($)
Restructuring Cost and Reserve [Line Items]
Charges	$ 6,618
Restructuring Reserve	4,071
Employee severance
Restructuring Cost and Reserve [Line Items]
Charges	2,757
Cash Payments Made in the Three Months Ended September 30, 2017	(2,547)
Restructuring Reserve	210
Lease termination fees and AROs for station closures
Restructuring Cost and Reserve [Line Items]
Charges	3,861
Cash Payments Made in the Three Months Ended September 30, 2017	0
Restructuring Reserve	$ 3,861

Acquisitions and Divestitures (Details)				3 Months Ended		6 Months Ended	9 Months Ended
Acquisitions and Divestitures (Details)	Jun. 22, 2017 USD ($)	Mar. 31, 2017 USD ($)	Feb. 27, 2017 USD ($) facility	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) shares	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Acquisition and Divestitures
Gain from sale of certain assets of subsidiary				$ 0	$ 0		$ 69,886,000	$ 0
Goodwill				68,082,000		$ 68,082,000	68,082,000		$ 93,018,000
BP Products North America, Inc.
Acquisition and Divestitures
Production facilities to be developed \| facility			2
Asset purchase agreement, amount		$ 155,511,000
Extinguishment of debt, amount		8,820,000
Asset purchase agreement, cash paid		30,000,000				1,007,000
Asset purchase agreement, debt instrument, face amount		123,487,000
Asset purchase agreement, post-closing adjustments, payment	$ 2,010,000
Gain from sale of certain assets of subsidiary	$ 762,000						69,886,000
Asset purchase agreement, contingent consideration (up to)			$ 25,000,000
Asset purchase agreement, contingent consideration, term			5 years
Asset purchase agreement, payment of transaction costs		$ 3,695,000				$ 8,605,000
Asset Purchase agreement, shares issued (in shares) \| shares						770,269
Asset purchase agreement, shares issued, value						$ 1,964,000
Proceeds from sale of other assets						142,190,000
Goodwill				$ 26,576,000		$ 26,576,000	$ 26,576,000

Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Cash and Cash Equivalents [Abstract]
Cash in excess of insurance limits	$ 43,200	$ 34,439

Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Restricted Cash
Short-term restricted cash	$ 1,463	$ 6,996
Canton Bonds
Restricted Cash
Short-term restricted cash	0	3,665
Held in Escrow
Restricted Cash
Short-term restricted cash	0	1,578
Standby letters of credit
Restricted Cash
Short-term restricted cash	$ 1,463	$ 1,753

Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Short-term investments
Amortized Cost	$ 151,666	$ 73,729
Gross Unrealized Losses	(145)	(11)
Estimated Fair Value	151,521	73,718
Municipal bonds and notes
Short-term investments
Amortized Cost	21,470	8,791
Gross Unrealized Losses	(73)	(4)
Estimated Fair Value	21,397	8,787
Zero coupon bonds
Short-term investments
Amortized Cost	69,192
Gross Unrealized Losses	(59)
Estimated Fair Value	69,133
Corporate bonds
Short-term investments
Amortized Cost	39,596	21,517
Gross Unrealized Losses	(13)	(7)
Estimated Fair Value	39,583	21,510
Certificate of deposits
Short-term investments
Amortized Cost	21,408	43,421
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 21,408	$ 43,421

Fair Value Measurements - Assets and Liabilities (Details) - Fair value measured on recurring basis - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Municipal bonds and notes
Assets:
Available-for-sale securities	$ 21,397	$ 8,787
Zero coupon bonds
Assets:
Available-for-sale securities	69,133
Corporate bonds
Assets:
Available-for-sale securities	39,583	21,510
Certificate of deposits
Assets:
Available-for-sale securities	21,408	43,421
Warrants
Liabilities:
Warrants	543	581
Level 2 \| Municipal bonds and notes
Assets:
Available-for-sale securities	21,397	8,787
Level 2 \| Zero coupon bonds
Assets:
Available-for-sale securities	69,133
Level 2 \| Corporate bonds
Assets:
Available-for-sale securities	39,583	21,510
Level 2 \| Certificate of deposits
Assets:
Available-for-sale securities	21,408	43,421
Level 3 \| Warrants
Liabilities:
Warrants	$ 543	$ 581

Fair Value Measurements (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Fair Value Measurements (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 29, 2017
Fair Value Measurements
Asset impairment charge	$ 60,666	$ 0	$ 60,666	$ 0
Fair Value, Measurements, Nonrecurring \| Level 3
Fair Value Measurements
Impaired long-lived assets	6,709		6,709		$ 59,367
Asset impairment charge	52,658
Natural Gas Fueling Stations \| Facility Closing \| Fair Value, Measurements, Nonrecurring \| Level 3
Fair Value Measurements
Impaired long-lived assets	2,886		2,886		$ 23,270
Asset impairment charge	$ 20,384		$ 52,658

Other Receivables (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Other Receivables
Other receivables	$ 16,253	$ 21,934
Loans to customers to finance vehicle purchases
Other Receivables
Other receivables	6,896	7,416
Accrued customer billings
Other Receivables
Other receivables	6,328	4,308
Fuel tax credits
Other Receivables
Other receivables	0	6,358
Other
Other Receivables
Other receivables	$ 3,029	$ 3,852

Inventory (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Inventory (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Inventory Disclosure [Abstract]
Inventory valuation provision	$ 13,158	$ 0	$ 13,158	$ 0
Raw materials and spare parts	42,487		42,487		$ 24,843
Work in process	806		806		845
Finished goods	1,331		1,331		3,856
Total inventories	44,624		44,624		$ 29,544
Station Closures \| Discontinued Operations, Held-for-sale or Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Inventory, net held-for-sale	$ 19,394		$ 19,394

Land, Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Land, Property and Equipment
Land, property and equipment, gross	$ 629,239		$ 629,239		$ 752,407
Less: accumulated depreciation	(265,466)		(265,466)		(268,484)
Total land, property and equipment, net	363,773		363,773		483,923
Capitalized software costs	27,056		27,056		25,728
Accumulated amortization on the capitalized software costs	20,371		20,371		17,237
Amortization expense related to the capitalized software costs	1,140	$ 824	3,134	$ 2,609
Property and equipment purchases included in accounts payable and accrued liabilities	2,007		2,007		4,139
Station Closures \| Discontinued Operations, Held-for-sale or Disposed of by Sale
Land, Property and Equipment
Inventory, net held-for-sale	19,394		19,394
Land
Land, Property and Equipment
Land, property and equipment, gross	2,858		2,858		2,858
LNG liquefaction plants
Land, Property and Equipment
Land, property and equipment, gross	94,633		94,633		94,634
RNG plants
Land, Property and Equipment
Land, property and equipment, gross	0		0		47,545
Station equipment
Land, Property and Equipment
Land, property and equipment, gross	298,681		298,681		341,605
Trailers
Land, Property and Equipment
Land, property and equipment, gross	59,312		59,312		54,985
Other equipment
Land, Property and Equipment
Land, property and equipment, gross	94,389		94,389		93,118
Construction in progress
Land, Property and Equipment
Land, property and equipment, gross	$ 79,366		$ 79,366		$ 117,662

Investments in Other Entities and Noncontrolling Interest in a Subsidiary (Details) - USD ($) $ in Thousands			3 Months Ended		9 Months Ended
	Jul. 14, 2017	Jun. 28, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Oct. 14, 2014	Sep. 16, 2014
Acquisition and Divestitures
Loss from equity method investments			$ 30	$ 13	$ 100	$ 20
Capital from equity method investment					0	3,031
Loss from noncontrolling interest			747	391
NG Advantage
Acquisition and Divestitures
Loss from noncontrolling interest			747	391	1,813	1,317
Noncontrolling interest, fair value			$ 23,009		$ 23,009		$ 24,822
NG Advantage \| Preferred units
Acquisition and Divestitures
Stock issued during period, value, acquisitions	$ 7,500
NG Advantage \| Common unit purchase agreement
Acquisition and Divestitures
Ownership interest acquired								53.30%
RNG Ventures
Acquisition and Divestitures
Ownership interest			100.00%		100.00%
Investment balance			$ 0		$ 0		833
Mansfield
Acquisition and Divestitures
Ownership interest									50.00%
Investment balance			1,542		1,542		$ 1,642
Loss from equity method investments			$ 30	$ 13	$ 100	$ 20
Capital from equity method investment		$ 3,031

Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Accrued alternative fuels incentives	$ 2,270	$ 9,840
Accrued employee benefits	3,999	4,317
Accrued interest	39	1,849
Accrued gas and equipment purchases	10,220	11,657
Accrued property and other taxes	4,164	4,572
Salaries and wages	8,636	12,293
Other	12,662	8,073
Total accrued liabilities	$ 41,990	$ 52,601

Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Feb. 29, 2016	Sep. 30, 2013	Jul. 11, 2011
Long-term debt
Principal Balances	$ 255,844	$ 314,348
Unamortized Debt Financing Costs	1,000	1,972
Balance, Net of Financing Costs	254,844	312,376
Principal Balances, amounts due within one year	(29,305)	(6,126)
Unamortized Debt Financing Costs, amounts due within one year	(58)	(183)
Balance, Net of Financing Costs, amounts due within one year	(29,247)	(5,943)
Principal Balances, long-term	226,539	308,222
Unamortized Debt Financing Costs, long-term	942	1,789
Balance, Net of Financing Costs, long-term	225,597	306,433
Related party notes	40,000	65,000
7.5% Notes
Long-term debt
Principal Balances	125,000	150,000
Unamortized Debt Financing Costs	155	274
Balance, Net of Financing Costs	$ 124,845	149,726
Interest rate	7.50%				7.50%
5.25% Notes
Long-term debt
Principal Balances	$ 110,450	110,450
Unamortized Debt Financing Costs	609	1,088
Balance, Net of Financing Costs	$ 109,841	109,362
Interest rate	5.25%			5.25%
Plains Credit Facility
Long-term debt
Principal Balances		23,500
Unamortized Debt Financing Costs		0
Balance, Net of Financing Costs		23,500
Interest rate			2.70%
Canton Bonds
Long-term debt
Principal Balances		9,520
Unamortized Debt Financing Costs		373
Balance, Net of Financing Costs		9,147
Capital lease obligations
Long-term debt
Principal Balances	$ 868	6,028
Unamortized Debt Financing Costs	0	0
Balance, Net of Financing Costs	868	6,028
NG Advantage debt
Long-term debt
Principal Balances	18,070	13,068
Unamortized Debt Financing Costs	236	237
Balance, Net of Financing Costs	17,834	12,831
Other debt
Long-term debt
Principal Balances	1,456	1,782
Unamortized Debt Financing Costs	0	0
Balance, Net of Financing Costs	$ 1,456	$ 1,782

Debt - 7.5% Notes (Details) - 7.5% Notes				3 Months Ended	9 Months Ended
Debt - 7.5% Notes (Details) - 7.5% Notes	Feb. 09, 2017 USD ($)	Jun. 14, 2013 USD ($) day $ / shares	Jul. 11, 2011 USD ($) note	Sep. 30, 2017 USD ($)	Sep. 30, 2017 USD ($)	Feb. 27, 2017 USD ($)	Aug. 27, 2013 USD ($)
Long-term debt
Interest rate			7.50%	7.50%	7.50%
Financing commitment received (up to)			$ 150,000,000
Number of debt instruments \| note			3
Financing commitment, issuance period			3 years
Principal amount of each debt instrument to be issued			$ 50,000,000
Buyers
Long-term debt
Additional amount of advances under the obligation assumed		$ 50,000,000
Amount of advance funded		$ 50,000,000
Conversion price of shares (in dollars per share) \| $ / shares		$ 15.80
Percentage of the trade price of common stock that the conversion price must be at premium for the Company to force conversion		40.00%
Number of days within 30 consecutive trading days in which the trade price of the entity's common stock must be at premium of the conversion price for the Company to force conversion (at least) \| day		20
Number of consecutive trading days used to determine the conversion obligation on the notes for the Company to force conversion		30 days
Period during which the debt instrument principal balance is required to be paid following its issuance		7 years
Green Energy Investment Holdings, LLC
Long-term debt
Principal amount transferred						$ 11,800,000	$ 5,000,000
Aggregate principal amount							16,800,000
Green Energy Investment Holdings, LLC \| Boone Pickens
Long-term debt
Debt instrument, repurchase amount during period	$ 25,000,000
Payments for repurchase and retirement of debt instrument	$ 21,750,000
Gain (loss) on repurchase of debt instrument				$ 3,191,000	$ 3,191,000
Aggregate principal amount							40,000,000
Green Energy Investment Holdings, LLC \| Other Third Parties
Long-term debt
Aggregate principal amount							$ 68,200,000

Debt - 5.25% Notes (Details) - 5.25% Notes		1 Months Ended	12 Months Ended
Debt - 5.25% Notes (Details) - 5.25% Notes	May 04, 2016 USD ($) shares	Sep. 30, 2013 USD ($) day $ / shares	Dec. 31, 2016 USD ($)	Sep. 30, 2017 USD ($)
Long-term debt
Interest rate		5.25%		5.25%
Debt issuance amount		$ 250,000,000
Payment of certain debt issuance costs		7,805,000
Amount of advance funded		$ 242,195,000
Conversion rate of debt instrument (shares per USD)		0.0641026
Conversion price of shares (in dollars per share) \| $ / shares		$ 15.60
Number of days within 30 consecutive trading days in which the trade price of the entity's common stock must be at premium of the conversion price for the Company to force conversion (at least) \| day		20
Number of consecutive trading days used to determine the conversion obligation on the notes for the Company to force conversion		30 days
Percentage of the trade price of common stock that the conversion price must be at premium for the Company to force conversion		160.00%
Redemption price as percentage of principal amount of notes to be redeemed		100.00%
Amount of sinking fund				$ 0
Percentage of principal amount at which notes may be required to be repurchased in event of fundamental change by the entity		100.00%
Payments for repurchase and retirement of debt instrument			$ 84,344,000
Debt instrument, repurchase amount during period			114,550,000
Stock issued during period (in shares) \| shares	6,265,829
Amount of debt converted	$ 25,000,000
Gain (loss) on repurchase of debt instrument			35,239,000
Purchaser
Long-term debt
Repayment of accrued interest			$ 1,546,000
Minimum
Long-term debt
Percentage of principal amount of notes outstanding allowing holders to accelerate all amounts due under notes in event of default under the Indenture (at least)		25.00%

Debt - Plains Credit Facility (Details) - Plains Credit Facility - USD ($)	Feb. 29, 2016	Dec. 22, 2016
Long-term debt
Line of credit limit	$ 50,000,000
Period during which the debt instrument principal balance is required to be paid following its issuance	1 year
Long-term Line of Credit		$ 23,500,000
Interest rate	2.70%
LIBOR
Long-term debt
Percentage of margin added to reference rate to determine interest rate on debt	2.30%

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References + Details

Debt - Other Debt (Details)	Sep. 30, 2017 USD ($)	Jan. 24, 2017 USD ($) installment	Dec. 31, 2016 USD ($)	Nov. 30, 2016 USD ($) installment	May 12, 2016 USD ($) installment	Mar. 19, 2014 USD ($)
Long-term debt
Debt and capital lease obligations	$ 254,844,000		$ 312,376,000
Canton Bonds
Long-term debt
Debt and capital lease obligations			$ 9,147,000
LSA \| 4.41% Term Loan \| Commerce
Long-term debt
Debt issuance amount					$ 6,300,000
Number of monthly installments \| installment					84
Interest rate					4.41%
LSA \| 5.0% Term Loan \| Commerce
Long-term debt
Debt issuance amount		$ 6,150,000
Number of monthly installments \| installment		84
Interest rate		5.00%
LSA \| 5.17% Term Loan \| Wintrust
Long-term debt
Debt issuance amount				$ 4,695,000
Number of monthly installments \| installment				72
Interest rate				5.17%
Trailer And Equipment Debt
Long-term debt
Weighted average interest rate	5.56%		5.51%
Debt and capital lease obligations	$ 3,222,000		$ 2,598,000
Trailer And Equipment Debt \| Maximum
Long-term debt
Interest rate	6.01%
Other Debt
Long-term debt
Weighted average interest rate	6.35%		5.72%
Debt and capital lease obligations	$ 1,456,000		$ 1,782,000
Other Debt \| Maximum
Long-term debt
Interest rate	19.69%
Canton Renewables \| Canton Bonds
Long-term debt
Debt issuance amount						$ 12,400,000

Net Loss Per Share (Details) - USD ($)	3 Months Ended		9 Months Ended
Net Loss Per Share (Details) - USD ($)	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 21, 2016
Earnings Per Share [Abstract]
Weighted-average common shares outstanding (in shares)	150,927,825	130,436,038	150,128,204	112,819,041
Securities Financing Transaction [Line Items]
Fees and issuance costs			$ 638,000	$ 1,340,000
Citigroup Global Markets Inc. \| Equity Distribution Agreement
Securities Financing Transaction [Line Items]
Equity financing agreement, amount authorized (up to)					$ 200,000,000
Gross proceeds	$ 0	$ 16,066,000	10,767,000	69,113,000
Fees and issuance costs	0	386,000	311,000	1,728,000
Net proceeds	$ 0	$ 15,680,000	$ 10,456,000	$ 67,385,000
Shares issued (in shares)	0	3,824,144	3,802,500	21,325,587

Net Loss Per Share - Anti-dilutive Securities (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net Loss Per Share
Anti-dilutive securities (in shares)	27,043,400	35,021,512	27,043,400	35,021,512
Stock Options
Net Loss Per Share
Anti-dilutive securities (in shares)	9,648,613	11,582,091	9,648,613	11,582,091
Convertible Notes
Net Loss Per Share
Anti-dilutive securities (in shares)	14,991,521	21,006,491	14,991,521	21,006,491
Restricted Stock Units
Net Loss Per Share
Anti-dilutive securities (in shares)	2,403,266	2,432,930	2,403,266	2,432,930

Stock-Based Compensation (Details) - USD ($)	3 Months Ended		9 Months Ended
Stock-Based Compensation (Details) - USD ($)	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Restructuring Cost and Reserve [Line Items]
Stock-based compensation expense, net of $0 tax in 2016 and 2017	$ 2,216,000	$ 2,077,000	$ 6,904,000	$ 6,533,000
Stock-based compensation expense, tax	0	$ 0	0	$ 0
Unrecognized compensation cost	7,194,000		$ 7,194,000
Unrecognized compensation cost, weighted-average period			1 year 7 months 6 days
Employee severance
Restructuring Cost and Reserve [Line Items]
Stock-based compensation expense, net of $0 tax in 2016 and 2017	$ 300,000		$ 300,000

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income tax benefit (expense)	$ 44	$ (416)	$ 2,183	$ (1,229)
Decrease in deferred tax liability, reduction in goodwill			2,493
Decrease in deferred tax assets, operating loss carryforwards			29,768
Decrease in deferred tax asset valuation allowance			$ 29,768

Alternative Fuels Excise Tax Credit (Details) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 $ / gallon
Alternative Fuels Excise Tax Credit
Federal fuel tax credit - CNG (in dollars per gasoline gallon equivalent)			0.50
Federal fuel tax credit - LNG (in dollars per liquid gallon)			0.50
VETC credits recognized as revenue \| $	$ 6,693	$ 19,609

Recently Issued and Adopted Accounting Standards (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Jan. 01, 2017
Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating loss carryforwards		$ 8,600
Deferred tax assets, valuation allowance	$ 8,600
Retained Earnings \| Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle in period of adoption		$ 194
New Accounting Pronouncement, Early Adoption, Effect \| Retained Earnings \| Accounting Standards Update 2016-16
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle in period of adoption	$ 302

Subsequent Events (Details) $ in Thousands	Oct. 23, 2017 USD ($)
Subsequent Event
Subsequent Event [Line Items]
Asset purchase agreement, cash paid	$ 5,486