Restatement of Previously Issued Consolidated Financial Statements - Consolidated Statements of Income (Details) - USD ($) $ / shares in Units, $ 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
Net revenue:
Net revenue	$ 309,099	$ 107,048	$ 67,995	$ 40,819	$ 91,607	$ 59,392	$ 57,466	$ 21,510		$ 78,976		$ 138,368
Net revenue		107,048	67,995	40,819	91,607				$ 108,814		$ 215,862		$ (93,237)	$ 229,975	$ 174,215
Cost of revenue:
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
Gross (loss) profit	(431,114)	(28,584)	(15)	(9,703)	7,746	4,500	6,142	(7,740)	(9,718)	(1,598)	(38,302)	2,902	(469,416)	10,648	(26,004)
Operating expenses:
Research and development		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
Selling, general and administrative		17,210	21,644	11,109	9,973	10,395	13,613	9,221	32,753	22,834	49,963	33,229	79,348	43,202	37,685
Change in fair value of contingent consideration		1,130									1,130		1,160
Total operating expenses	46,660	25,726	26,517	15,883	14,855	13,958	17,221	12,227	42,400	29,448	68,126	43,406	114,786	58,261	50,435
Operating loss	(477,774)	(54,310)	(26,532)	(25,586)	(7,109)	(9,458)	(11,079)	(19,967)	(52,118)	(31,046)	(106,428)	(40,504)	(584,202)	(47,613)	(76,439)
Interest and other expense, net		(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)
Change in fair value of common stock warrant liability					72	427	1,706	(2,126)		(420)		7		79	4,286
Impairment of long-lived assets													(6,430)
Gain (loss) on extinguishment of debt			13,222			(518)		(518)	13,222	(518)	13,222	(518)	17,686	(518)
Loss before income taxes		(71,861)	(26,772)	(37,432)	(18,036)	(17,822)	(17,338)	(30,547)	(64,204)	(47,885)	(136,065)	(65,707)	(627,000)	(83,743)	(94,903)
Income tax benefit		6,644	17,371						17,371		24,015		30,845		9,295
Net loss attributable to the Company		(65,217)	(9,401)	(37,432)	(18,036)	(17,822)	(17,338)	(30,547)	(46,833)	(47,885)	(112,050)	(65,707)	(596,155)	(83,743)	(85,608)
Preferred stock dividends declared, deemed dividends and accretion of discount			(13)	(13)	(1,241)	(544)	(13)	(13)	(26)	(26)	(26)	(570)	(26)	(1,812)	(52)
Net loss attributable to common shareholders	$ (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)
Net loss per share:
Basic and diluted	$ (1.35)	$ (0.18)	$ (0.03)	$ (0.12)	$ (0.07)	$ (0.08)	$ (0.08)	$ (0.14)	$ (0.15)	$ (0.21)	$ (0.34)	$ (0.29)	$ (1.68)	$ (0.36)	$ (0.39)
Weighted average number of common stock outstanding		371,010,544	316,645,050	305,192,201	260,053,150	236,759,521	231,114,868	220,605,068	310,918,626	225,899,224	330,949,265	229,519,323	354,790,106	237,152,780	218,882,337
Sales of fuel cell systems and related infrastructure
Net revenue:
Net revenue	$ (246,171)	$ 83,662	$ 47,746	$ 20,468	$ 69,785	$ 38,883	$ 38,702	$ 2,550	$ 68,214	$ 41,252	$ 151,876	$ 80,135	$ (94,295)	$ 149,920	$ 107,175
Cost of revenue:
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
Services performed on fuel cell systems and related infrastructure
Net revenue:
Net revenue	(29,387)	6,829	6,236	6,521	7,328	6,205	5,341	6,343	12,757	11,684	19,586	17,889	(9,801)	25,217	22,002
Cost of revenue:
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
Provision (benefit) for loss contracts related to service
Cost of revenue:
Total cost of revenue		25,147	706	95	13	206	363	162	801	201	25,948	407	35,473	394	5,345
Power Purchase Agreements
Net revenue:
Net revenue	6,991	6,629	6,579	6,421	6,664	6,520	6,334	6,035	13,000	12,369	19,629	18,889	26,620	25,553	22,569
Cost of revenue:
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
Fuel delivered to customers
Net revenue:
Net revenue	(40,608)	9,831	7,372	7,333	7,779	7,649	7,089	6,582	14,705	13,671	24,536	21,320	(16,072)	29,099	22,469
Cost of revenue:
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
Other
Net revenue:
Net revenue	$ 76	97	62	76	51	135			138		235	135	311	186
Cost of revenue:
Total cost of revenue		131	63	81	50	150			144		275	150	$ 323	200
As previously Reported
Net revenue:
Net revenue						59,461	57,535	21,579		79,114		138,575
Net revenue		106,989	68,070	40,813	91,664				108,883		215,872			230,239	174,632
Cost of revenue:
Total cost of revenue		108,279	62,994	45,284	78,882	51,114	46,914	25,363	108,278	72,277	216,557	123,391		202,273	172,010
Gross (loss) profit		(1,290)	5,076	(4,471)	12,782	8,347	10,621	(3,784)	605	6,837	(685)	15,184		27,966	2,622
Operating expenses:
Research and development		11,964	9,757	10,412	9,341	8,028	8,933	7,373	20,169	16,306	32,133	24,334		33,675	33,907
Selling, general and administrative		14,277	21,658	11,013	10,982	10,400	13,627	9,324	32,671	22,951	46,948	33,351		44,333	38,198
Total operating expenses		26,241	31,415	21,425	20,323	18,428	22,560	16,697	52,840	39,257	79,081	57,685		78,008	72,105
Operating loss		(27,531)	(26,339)	(25,896)	(7,541)	(10,081)	(11,939)	(20,481)	(52,235)	(32,420)	(79,766)	(42,501)		(50,042)	(69,483)
Interest and other expense, net		(17,241)	(13,198)	(11,583)	(10,806)	(7,972)	(7,861)	(8,345)	(24,781)	(16,206)	(42,022)	(24,178)		(35,502)	(22,135)
Change in fair value of common stock warrant liability		(1,130)			72	427	1,706	(2,126)		(420)	(1,130)	7		79	4,286
Gain (loss) on extinguishment of debt			13,222			(518)			13,222		13,222	(518)
Loss before income taxes		(45,902)	(26,315)	(37,479)	(18,275)	(18,144)	(18,094)	(30,952)	(63,794)	(49,046)	(109,696)	(67,190)		(85,465)	(87,332)
Income tax benefit		6,523	17,659						17,659		24,182				9,217
Net loss attributable to the Company		(39,379)	(8,656)	(37,479)	(18,275)	(18,144)	(18,094)	(30,952)	(46,135)	(49,046)	(85,514)	(67,190)		(85,465)	(78,115)
Preferred stock dividends declared, deemed dividends and accretion of discount			(13)	(13)	(13)	(13)	(13)	(52)	(19)	(26)	(19)	(39)		(52)	(52)
Net loss attributable to common shareholders		$ (39,379)	$ (8,669)	$ (37,492)	$ (18,288)	$ (18,157)	$ (18,107)	$ (31,004)	$ (46,154)	$ (49,072)	$ (85,533)	$ (67,229)		$ (85,517)	$ (78,167)
Net loss per share:
Basic and diluted		$ (0.11)	$ (0.03)	$ (0.12)	$ (0.07)	$ (0.08)	$ (0.08)	$ (0.14)	$ (0.15)	$ (0.22)	$ (0.26)	$ (0.29)		$ (0.36)	$ (0.36)
Weighted average number of common stock outstanding		371,010,544	316,645,050	305,192,201	260,053,150	236,759,521	231,114,868	220,605,068	310,918,626	225,899,224	330,949,265	229,519,323		237,152,780	218,882,337
As previously Reported | Sales of fuel cell systems and related infrastructure
Net revenue:
Net revenue		$ 83,528	$ 47,746	$ 20,387	$ 69,767	$ 38,877	$ 38,696	$ 2,544	$ 68,133	$ 41,240	$ 151,661	$ 80,117		$ 149,884	$ 107,292
Cost of revenue:
Total cost of revenue		68,509	33,676	13,744	46,419	24,990	23,129	2,321	47,420	25,450	115,929	50,440		96,859	84,439
As previously Reported | Services performed on fuel cell systems and related infrastructure
Net revenue:
Net revenue		6,829	6,236	6,521	7,328	6,205	5,341	6,343	12,757	11,684	19,586	17,889		25,217	22,002
Cost of revenue:
Total cost of revenue		7,074	6,491	8,181	9,999	6,461	6,218	6,123	14,672	12,341	21,746	18,802		28,801	23,698
As previously Reported | Provision (benefit) for loss contracts related to service
Cost of revenue:
Total cost of revenue		4,306									4,306
As previously Reported | Power Purchase Agreements
Net revenue:
Net revenue		6,704	6,654	6,496	6,739	6,595	6,409	6,110	13,150	12,519	19,854	19,114		25,853	22,869
Cost of revenue:
Total cost of revenue		14,087	13,704	14,243	11,992	10,353	8,713	8,998	27,947	17,711	42,034	28,064		40,056	36,161
As previously Reported | Fuel delivered to customers
Net revenue:
Net revenue		9,831	7,372	7,333	7,779	7,649	7,089	6,582	14,705	13,671	24,536	21,320		29,099	22,469
Cost of revenue:
Total cost of revenue		14,172	9,060	9,035	10,422	9,160	8,854	7,921	18,095	16,775	32,267	25,935		36,357	27,712
As previously Reported | Other
Net revenue:
Net revenue		97	62	76	51	135			138		235	135		186
Cost of revenue:
Total cost of revenue		131	63	81	50	150			144		275	150		200
Restatement Adjustments
Net revenue:
Net revenue						(69)	(69)	(69)		(138)		(207)
Net revenue		59	(75)	6	(57)				(69)		(10)			(264)	(417)
Cost of revenue:
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
Gross (loss) profit		(27,294)	(5,091)	(5,232)	(5,036)	(3,847)	(4,479)	(3,956)	(10,323)	(8,435)	(37,617)	(12,282)		(17,318)	(28,626)
Operating expenses:
Research and development		(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)
Selling, general and administrative		2,933	(14)	96	(1,009)	(5)	(14)	(103)	82	(117)	3,015	(122)		(1,131)	(513)
Change in fair value of contingent consideration		1,130									1,130
Total operating expenses		(515)	(4,898)	(5,542)	(5,468)	(4,470)	(5,339)	(4,470)	(10,440)	(9,809)	(10,955)	(14,279)		(19,747)	(21,670)
Operating loss		(26,779)	(193)	310	432	623	860	514	117	1,374	(26,662)	1,997		2,429	(6,956)
Interest and other expense, net		(310)	(264)	(263)	(193)	(301)	(104)	(109)	(527)	(213)	(837)	(514)		(189)	(615)
Change in fair value of common stock warrant liability		1,130									1,130
Gain (loss) on extinguishment of debt								(518)		(518)		(518)		(518)
Loss before income taxes		(25,959)	(457)	47	239	322	756	405	(410)	1,161	(26,369)	1,483		1,722	(7,571)
Income tax benefit		121	(288)						(288)		(167)				78
Net loss attributable to the Company		(25,838)	(745)	47	239	322	756	405	(698)	1,161	(26,536)	1,483		1,722	(7,493)
Preferred stock dividends declared, deemed dividends and accretion of discount					(1,228)	(531)		39	(7)		(7)	(531)		(1,760)
Net loss attributable to common shareholders		(25,838)	(745)	47	(989)	(209)	756	444	(705)	1,161	(26,543)	952		(38)	(7,493)
Restatement Adjustments | Sales of fuel cell systems and related infrastructure
Net revenue:
Net revenue		134		81	18	6	6	6	81	12	215	18		36	(117)
Cost of revenue:
Total cost of revenue		919	212	230	672	193	200	(9)	442	191	1,361	384		1,056	766
Restatement Adjustments | Services performed on fuel cell systems and related infrastructure
Cost of revenue:
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 | Provision (benefit) for loss contracts related to service
Cost of revenue:
Total cost of revenue		20,841	706	95	13	206	363	162	801	201	21,642	407		394	5,345
Restatement Adjustments | Power Purchase Agreements
Net revenue:
Net revenue		(75)	(75)	(75)	(75)	(75)	(75)	(75)	(150)	(150)	(225)	(225)		(300)	(300)
Cost of revenue:
Total cost of revenue		657	800	528	309	461	116	835	1,328	951	1,985	1,412		1,721	5,200
Restatement Adjustments | Fuel delivered to customers
Net revenue:
Net revenue														8,846	8,325
Cost of revenue:
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