Nature of Operations (Details) $ / shares in Units, $ in Thousands, shares in Millions						1 Months Ended						3 Months Ended			6 Months Ended
	Jul. 10, 2020 USD ($)	Jul. 01, 2020 shares	Jun. 10, 2020 USD ($)	May 06, 2020 USD ($)	Apr. 13, 2020 USD ($)	May 31, 2020 USD ($)	Dec. 31, 2019 USD ($) $ / shares shares	Nov. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)	Apr. 30, 2019 USD ($)	Mar. 31, 2019 USD ($) $ / shares shares	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($) shares	Mar. 31, 2019 USD ($) $ / shares shares	Jun. 30, 2020 USD ($) item	Jun. 30, 2019 USD ($)	May 05, 2020	Mar. 31, 2020 USD ($)
Liquidity
Number of fuel cell systems deployed | item															34,000
Net loss attributable to common shareholders												$ 8,669	$ 18,107		$ 46,154	$ 49,072
Accumulated deficit							$ 1,345,807					1,391,961			1,391,961
Net cash used in operating activities															111,247	48,488
Net loss attributable to the Company												(8,656)	$ (18,094)		(46,135)	(49,046)
Net outflows from fluctuations in working capital and other assets and liabilities															61,100
Cash and cash equivalents							139,496					152,492			152,492
Net working capital							$ 162,500					$ 186,300			186,300
Net cash used in investing activities															(56,551)	(6,316)
Net cash provided by financing activities															181,565	80,026
Number of common stock sold | shares											10.0
Share price (in dollars per share) | $ / shares											$ 2.35			$ 2.35
Proceeds from public offerings, net of transaction costs											$ 23,500				$ (269)	28,265
Interest rate (as a percent)												9.50%			9.50%
Proceeds from issuance of convertible senior notes, net															$ 205,100
Net proceeds			$ 25,000												27,678	25,609
Conversion of notes through common stock issuance | shares		16.0
Remaining lease payments												$ 293,700			293,700
Security on lease												233,800			233,800
Letter of credit												98,200			98,200
Value of shares issued															(269)	28,265
Repayments of finance obligations															11,783	$ 56,070
Incremental term loan												141,200			141,200
Secured term loan facility
Liquidity
Proceeds from borrowing of long-term debt								$ 20,000
Wells Fargo
Liquidity
Remaining lease payments												103,200			$ 103,200
Sale/leaseback transactions under Wells Fargo MLA | item															0
Letter of credit												50,600			$ 50,600
Financial Institutions
Liquidity
Remaining lease payments												190,500			190,500
Cash collateral for unguaranteed portions												172,300			172,300
Loan and security agreement | Secured term loan facility
Liquidity
Interest rate (as a percent)				9.50%													12.00%
Proceeds from borrowing of long-term debt				$ 50,000
Outstanding balance												141,200			141,200
Incremental term loan				50,000
Additional loan				$ 50,000
Loan and security agreement | Secured term loan facility | Subsequent event
Liquidity
Additional amount borrowed	$ 25,000
Loan and security agreement | Generate Lending, LLC
Liquidity
Repayments of finance obligations											17,600
Termination of certain equipment leases											50,300
Loan and security agreement | Generate Lending, LLC | Secured term loan facility
Liquidity
Principal amount											100,000			$ 100,000
Interest rate (as a percent)								12.00%
Proceeds from borrowing of long-term debt								$ 20,000		$ 15,000	$ 85,000
Outstanding balance																		$ 107,500
Convertible Senior Notes
Liquidity
Interest rate (as a percent)						3.75%			7.50%
$200M Convertible Senior Notes
Liquidity
Interest rate (as a percent)						5.50%
Debt Instrument, Repurchased Face Amount						$ 66,300
$40M Convertible Senior Note
Liquidity
Principal amount									$ 40,000
Interest rate (as a percent)									7.50%
Obligation, net of interest accretion									$ 48,000
Carrying amount of debt												$ 41,000			41,000
Proceeds from borrowing of long-term debt									$ 39,100
$212.8M Convertible Senior Notes
Liquidity
Principal amount						$ 212,800
Interest rate (as a percent)						3.75%
Proceeds from issuance of convertible senior notes, net						$ 205,100
Net proceeds															$ 90,200
5.5 % Covertable Senior Notes
Liquidity
Payments for Repurchase of Convertible Debt						66,300
Payment for Derivative Contract						$ 15,300
At Market Issuance Sales Agreement
Liquidity
Authorized amount					$ 75,000
Number of common stock sold | shares													2.1	0.0
Proceeds from public offerings, net of transaction costs													$ 5,500
Public Offerings
Liquidity
Number of common stock sold | shares							46.0				10.0
Share price (in dollars per share) | $ / shares							$ 2.75				$ 2.35			$ 2.35
Proceeds from public offerings, net of transaction costs							$ 120,400				$ 23,500