Revenue - Changes in contract assets and contract liabilities (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Contract assets
Impairment	$ (38,300)		$ (2,400)
Net change in contract assets		$ 2,493	40,258	$ 39,515
Contract liabilities
Increases due to customer billings, net of amounts recognized as revenue during the period		74,702	151,965
Change in contract liabilities related to warrants		440	440
Revenue recognized that was included in the contract liability balance as of the beginning of the period		(160,819)	(94,001)
Net change in deferred revenue and contract liabilities		(85,677)	58,404
Sales of fuel cell systems
Contract assets
Transferred to receivables from contract assets recognized at the beginning of the period		(27,513)	(94,860)
Change in contract assets related to warrants		(4,909)	14,260
Impairment		(35,118)	(2,375)
Revenue recognized and not billed as of the end of the period		29,566	134,677
Net change in contract assets		$ (37,974)	$ 51,702