Consolidated Statements of Operations - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Net revenue:    
Net revenue $ 18,593 $ 26,418
Cost of revenue:    
Total cost of revenue 25,363 30,402
Gross loss (6,770) (3,984)
Operating expenses:    
Research and development 7,373 8,648
Selling, general and administrative 9,324 8,309
Total operating expenses 16,697 16,957
Operating loss (23,467) (20,941)
Interest and other expense, net (8,345) (3,105)
Change in fair value of common stock warrant liability (2,126) 1,258
Loss before income taxes (33,938) (22,788)
Income tax benefit   2,953
Net loss attributable to the Company (33,938) (19,835)
Preferred stock dividends declared and accretion of discount (52) (13)
Net loss attributable to common shareholders $ (33,990) $ (19,848)
Net loss per share:    
Basic and diluted (in dollars per share) $ (0.15) $ (0.09)
Weighted average number of common shares outstanding 220,605,068 226,985,762
Sales of fuel cell systems and related infrastructure    
Net revenue:    
Net revenue $ 2,220 $ 10,613
Cost of revenue:    
Total cost of revenue 2,321 10,122
Services performed on fuel cell systems and related infrastructure    
Net revenue:    
Net revenue 6,213 5,483
Cost of revenue:    
Total cost of revenue 6,123 5,734
Power Purchase Agreements    
Net revenue:    
Net revenue 4,707 5,372
Cost of revenue:    
Total cost of revenue 8,998 8,650
Fuel delivered to customers    
Net revenue:    
Net revenue 5,453 4,950
Cost of revenue:    
Total cost of revenue $ 7,921 $ 5,896