Restatement of Previously Issued Consolidated Financial Statements - Restatement Background (Details) - USD ($) $ in Thousands	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2018
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Operating Lease, Right-of-Use Asset	$ 117,016	$ 90,184	$ 71,789	$ 64,812	$ 63,266	$ 47,016	$ 39,679	$ 33,599	$ 71,789	$ 39,679	$ 90,184	$ 47,016	$ 117,016	$ 63,266
Operating Lease, Liability	113,938												113,938
Total cost of revenue		135,632	68,010	50,522	83,861	54,892	51,324	29,250	118,532	80,574	254,164	135,466	376,179	219,327	$ 200,219
Net Income (Loss) Available to Common Stockholders, Basic	(484,105)	(65,217)	(9,414)	(37,445)	(19,277)	(18,366)	(17,351)	(30,560)	(46,859)	(47,911)	(112,076)	(66,277)	(596,181)	(85,555)	(85,660)
Increase in accumulated deficit	(1,946,488)	(1,462,377)	(1,397,160)	(1,387,752)	(1,350,307)	(1,332,259)	(1,314,425)	(1,297,072)	(1,397,160)	(1,314,425)	(1,462,377)	(1,332,259)	(1,946,488)	(1,350,307)
Research and Development Expense		7,386	4,873	4,774	4,882	3,563	3,608	3,006	9,647	6,614	17,033	10,177	27,848	15,059	12,750
Nonoperating Income (Expense)		(17,551)	(13,462)	(11,846)	(10,999)	(8,273)	(7,965)	(8,454)	(25,308)	(16,419)	(42,859)	(24,692)	(60,484)	(35,691)	(22,750)
Asset Impairment Charges													6,430
Right of use assets obtained in exchange for new operating lease liabilities													58,500	37,700
Other current liabilities	29,487	21,083	19,418	8,446	6,704	8,373	3,705	3,745	19,418	3,705	21,083	8,373	29,487	6,704
Other liabilities	40,447	45,170	14,476	2,386	2,818	2,834	3,333	3,746	14,476	3,333	45,170	2,834	40,447	2,818
Finance Lease, Liability	5,396												5,396
Finance obligations	32,717	31,349	28,794	26,209	24,667	20,469	12,455	11,028	28,794	12,455	31,349	20,469	32,717	24,667
Financing Transaction Finance Obligation Amount	$ 148,836	140,662	131,653	121,322	119,422	99,669	76,916	54,864	131,653	76,916	140,662	99,669	148,836	119,422
Series E Redeemable Convertible Preferred Stock
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Dividends, Preferred Stock														1,800
Provision (benefit) for loss contracts related to service
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total cost of revenue		25,147	706	95	13	206	363	162	801	201	25,948	407	35,473	394	5,345
Sales of fuel cell systems and related infrastructure
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total cost of revenue		69,428	33,888	13,974	47,091	25,183	23,329	2,312	47,862	25,641	117,290	50,824	171,404	97,915	85,205
Sales of fuel cell systems and related infrastructure | Revision of Research and Development Expense
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total cost of revenue														7,000
Fuel delivered to customers
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total cost of revenue		17,002	11,076	11,254	12,800	11,149	11,146	10,152	22,330	21,298	39,332	32,447	61,815	45,247	36,037
Fuel delivered to customers | Revision of Research and Development Expense
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total cost of revenue														8,900
Services performed on fuel cell systems and related infrastructure
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total cost of revenue		9,180	7,773	10,347	11,606	7,802	8,383	6,791	18,120	15,174	27,300	22,976	42,524	34,582	32,271
Power Purchase Agreements
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total cost of revenue		14,744	14,504	14,771	12,301	10,814	8,829	9,833	29,275	18,662	44,019	29,476	$ 64,640	41,777	41,361
Restatement Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Operating Lease, Right-of-Use Asset		90,184	71,789	64,812	63,266	47,016	39,679	33,599	71,789	39,679	90,184	47,016		63,266
Total cost of revenue		27,353	5,016	5,238	4,979	3,778	4,410	3,887	10,254	8,297	37,607	12,075		17,054	28,209
Net Income (Loss) Available to Common Stockholders, Basic		(25,838)	(745)	47	(989)	(209)	756	444	(705)	1,161	(26,543)	952		(38)	(7,493)
Increase in accumulated deficit		(31,037)	(5,199)	(4,453)	(4,500)	(4,741)	(5,062)	(5,817)	(5,199)	(5,062)	(31,037)	(4,741)		(4,500)
Research and Development Expense		(4,578)	(4,884)	(5,638)	(4,459)	(4,465)	(5,325)	(4,367)	(10,522)	(9,692)	(15,100)	(14,157)		(18,616)	(21,157)
Nonoperating Income (Expense)		(310)	(264)	(263)	(193)	(301)	(104)	(109)	(527)	(213)	(837)	(514)		(189)	(615)
Other current liabilities		3,803	(2,274)	(1,977)	(1,839)	(1,865)	688	1,474	(2,274)	688	3,803	(1,865)		(1,839)
Other liabilities		18,102	2,720	2,373	2,805	2,821	3,320	3,729	2,720	3,320	18,102	2,821		2,805
Finance obligations		(32,343)	(28,901)	(25,838)	(24,840)	(20,643)	(18,208)	(12,969)	(28,901)	(18,208)	(32,343)	(20,643)		(24,840)
Financing Transaction Finance Obligation Amount		(196,488)	(169,000)	(150,849)	(145,806)	(108,796)	(80,615)	(56,331)	(169,000)	(80,615)	(196,488)	(108,796)		(145,806)
Restatement Adjustments | Series E Redeemable Convertible Preferred Stock
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net Income (Loss) Available to Common Stockholders, Basic														1,800
Dividends, Preferred Stock														1,800	1,800
Restatement Adjustments | Revision of Lease Liability
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Increase in accumulated deficit					4,500									4,500	6,200
Restatement Adjustments | Revision of Deemed Dividend [Member] | Series E Redeemable Convertible Preferred Stock
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Deemed Dividend														1,800
Restatement Adjustments | Revision of Research and Development Expense
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total cost of revenue														1,100
Research and Development Expense														(19,492)	(21,157)
Restatement Adjustments | Cumulative effect from adoption of ASC 842
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Increase in accumulated deficit																$ 3,400
Restatement Adjustments | Provision (benefit) for loss contracts related to service
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total cost of revenue		20,841	706	95	13	206	363	162	801	201	21,642	407		394	5,345
Restatement Adjustments | Sales of fuel cell systems and related infrastructure
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total cost of revenue		919	212	230	672	193	200	(9)	442	191	1,361	384		1,056	766
Restatement Adjustments | Sales of fuel cell systems and related infrastructure | Revision of Research and Development Expense
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total cost of revenue															614
Restatement Adjustments | Fuel delivered to customers
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total cost of revenue		2,830	2,016	2,219	2,378	1,989	2,292	2,231	4,235	4,523	7,065	6,512		8,890	8,325
Restatement Adjustments | Fuel delivered to customers | Revision of Research and Development Expense
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total cost of revenue															8,300
Restatement Adjustments | Services performed on fuel cell systems and related infrastructure
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total cost of revenue		2,106	1,282	2,166	1,607	1,341	2,165	668	3,448	2,833	5,554	4,174		5,781	8,573
Restatement Adjustments | Services performed on fuel cell systems and related infrastructure | Revision of Research and Development Expense
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total cost of revenue														2,500	8,000
Restatement Adjustments | Power Purchase Agreements
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total cost of revenue		$ 657	$ 800	$ 528	$ 309	$ 461	$ 116	$ 835	$ 1,328	$ 951	$ 1,985	$ 1,412		$ 1,721	5,200
Restatement Adjustments | Power Purchase Agreements | Revision of Research and Development Expense
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total cost of revenue															$ 4,200