Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue:
Gross revenue	$ 39,927	$ 22,604	$ 69,007	$ 37,839
Provision for common stock warrants	(3,921)	(1,820)	(5,806)	(1,820)
Net revenue	36,006	20,784	63,201	36,019
Cost of revenue:
Total cost of revenue	38,316	24,327	69,495	44,041
Gross loss	(2,310)	(3,543)	(6,294)	(8,022)
Operating expenses:
Research and development	8,427	6,625	17,075	12,623
Selling, general and administrative	12,241	17,904	20,550	27,049
Total operating expenses	20,668	24,529	37,625	39,672
Operating loss	(22,978)	(28,072)	(43,919)	(47,694)
Interest and other expense, net	(6,136)	(2,251)	(9,241)	(4,388)
Change in fair value of common stock warrant liability	334	(12,296)	1,592	(14,576)
Loss before income taxes	(28,780)	(42,619)	(51,568)	(66,658)
Income tax benefit	2,912		5,865
Net loss attributable to the Company	(25,868)	(42,619)	(45,703)	(66,658)
Preferred stock dividends declared and accretion of discount	(13)	(26)	(26)	(3,061)
Net loss attributable to common shareholders	$ (25,881)	$ (42,645)	$ (45,729)	$ (69,719)
Net loss per share:
Basic and diluted (in dollars per share)	$ (0.12)	$ (0.19)	$ (0.21)	$ (0.34)
Weighted average number of common shares outstanding	214,315,312	220,310,678	220,650,537	205,748,184
Sales of fuel cell systems
Revenue:
Gross revenue	$ 20,622	$ 8,560	$ 32,080	$ 10,757
Cost of revenue:
Total cost of revenue	15,377	6,441	25,499	8,727
Services performed on fuel cell systems and related infrastructure
Revenue:
Gross revenue	7,188	5,049	13,786	10,198
Cost of revenue:
Total cost of revenue	7,125	5,068	13,995	11,634
Power purchase agreements
Revenue:
Gross revenue	5,629	4,945	11,118	9,256
Cost of revenue:
Total cost of revenue	9,393	7,450	17,684	14,065
Fuel delivered to customers
Revenue:
Gross revenue	6,488	3,986	12,023	7,477
Cost of revenue:
Total cost of revenue	$ 6,421	5,303	$ 12,317	9,452
Other
Revenue:
Gross revenue		64		151
Cost of revenue:
Total cost of revenue		$ 65		$ 163