Borrowings - Narrative (Details)									3 Months Ended			5 Months Ended	6 Months Ended			12 Months Ended
	Jun. 30, 2025 USD ($)	Jan. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)	Oct. 31, 2024 USD ($)	Aug. 31, 2024 USD ($)	Jun. 30, 2024 USD ($) $ / shares	Jun. 21, 2024 USD ($) tranche installment	Jul. 29, 2022 USD ($)	Jun. 30, 2024 USD ($) $ / shares	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Apr. 30, 2023 USD ($)	Jun. 30, 2024 USD ($) $ / shares	Dec. 31, 2023 USD ($) $ / shares	Jun. 30, 2023 USD ($) shares	Dec. 31, 2023 USD ($) $ / shares	Jan. 31, 2023 USD ($)	Jan. 18, 2023 USD ($) $ / shares	Sep. 30, 2021 USD ($)	Jul. 06, 2021 USD ($)
Debt Instrument [Line Items]
Proceeds from issuance of secured debt													$ 70,075,000		$ 0
Restricted cash minimum liquidity requirement amount						$ 2,500,000			$ 2,500,000				2,500,000
Loss on fair value of loans									$ 240,000	$ 0			$ 240,000		0
Common stock, par value (in dollars per share) | $ / shares						$ 0.0001			$ 0.0001				$ 0.0001	$ 0.0001		$ 0.0001
Long-term debt, current						$ 3,041,000			$ 3,041,000				$ 3,041,000	$ 3,332,000		$ 3,332,000
Proceeds from issuance of convertible notes - related party													0		48,050,000
Gain (loss) on debt extinguishment									68,478,000	(1,876,000)			68,478,000		(3,510,000)
Principal						218,141,000			218,141,000				218,141,000	238,962,000		238,962,000
Delayed Draw Term Loan | Secured Debt
Debt Instrument [Line Items]
Principal							$ 210,500,000
Number of installments | installment							4
Proceeds from issuance of secured debt						135,500,000	$ 75,000,000
Number of tranches | tranche							4
Initial direct costs							$ 3,750,000
Stated interest rate							15.00%
Percentage of additional debt instrument, interest rate							5.00%
Percentage of original issue discount							5.00%
Percentage of debt exit fee							5.00%
Restricted cash minimum liquidity requirement increases						5,000,000			5,000,000				5,000,000
Number of days prior to current maturity date							91 days
Percentage of debt milestones penalty							4.00%
Percentage of debt milestones penalty, net							16.00%
Debt instrument, milestones penalty percentage							49.00%
Percentage of credit agreement							33.00%
Debt instrument, writ or warrant excess amount							$ 2,500,000
Fair value of loans						25,893,000	$ 25,653,000		25,893,000				25,893,000
Loss on fair value of loans									240,000				240,000
Principal						75,000,000			75,000,000				75,000,000	0		0
Delayed Draw Term Loan | Secured Debt | Minimum
Debt Instrument [Line Items]
Percentage of additional debt instrument, interest rate							1.00%
Credit agreement approval term							90 days
Delayed Draw Term Loan | Secured Debt | Maximum
Debt Instrument [Line Items]
Percentage of additional debt instrument, interest rate							5.00%
Credit agreement approval term							240 days
Delayed Draw Term Loan | Secured Debt | Forecast
Debt Instrument [Line Items]
Proceeds from issuance of secured debt		$ 40,500,000		$ 65,000,000	$ 30,000,000
Delayed Draw Term Loan (DDTL), Additional Funding | Secured Debt
Debt Instrument [Line Items]
Number of tranches | tranche							3
Credit Facility | Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility borrowing capacity							$ 105,000,000
DOE Clean Energy Financing Program
Debt Instrument [Line Items]
Restricted cash minimum liquidity requirement increases						15,000,000			15,000,000				15,000,000
2021 Convertible Note Payable | Convertible Notes
Debt Instrument [Line Items]
Principal																				$ 100,000,000
Interest incurred and included in principal amount													3,474,000			3,373,000
Embedded conversion feature						53,000			53,000				53,000	78,000		78,000
Non-cash interest expense - related party									3,479,000	3,009,000			6,895,000		5,970,000
Amortization of debt discount									1,588,000	1,250,000			3,119,000		2,457,000
Principal						119,289,000			119,289,000				119,289,000	115,815,000		115,815,000
AFG Convertible Notes | Related Party
Debt Instrument [Line Items]
Fair value of loans																		$ 16,623,000
Interest incurred and included in principal amount													2,309,000	2,039,000
Non-cash interest expense - related party											$ 2,873,000
AFG Convertible Notes | Convertible Notes
Debt Instrument [Line Items]
Common stock, par value (in dollars per share) | $ / shares																		$ 0.0001
Conversion price per unit (in dollars per share) | $ / shares																		$ 1.67
AFG Convertible Notes | Convertible Notes | Related Party
Debt Instrument [Line Items]
Principal																	$ 13,750,000	$ 13,750,000
Paid-in-kind interest rate																	26.50%	26.50%
Embedded conversion feature						5,361,000			5,361,000				5,361,000	4,345,000		4,345,000
Non-cash interest expense - related party									1,433,000	1,129,000			2,868,000		2,098,000
Amortization of debt discount									218,000	210,000			436,000		358,000
Principal						19,738,000			19,738,000				19,738,000	17,429,000		17,429,000
Senior Secured Term Loan | Minimum | SOFR
Debt Instrument [Line Items]
Variable rate spread								0.2616%
Senior Secured Term Loan | Minimum | NYFRB
Debt Instrument [Line Items]
Variable rate spread								0.50%
Senior Secured Term Loan | Secured Debt
Debt Instrument [Line Items]
Principal								$ 100,000,000
Number of days prior to current maturity date								91 days
Interest escrowed for loan														11,755,000		11,755,000
Gain (loss) on debt extinguishment							68,478,000
Principal						0			0				0	100,000,000		100,000,000
Senior Secured Term Loan | Secured Debt | Atlas Credit Agreement
Debt Instrument [Line Items]
Principal							$ 100,000,000
Number of days prior to current maturity date							91 days
Interest escrowed for loan							$ 11,900,000
Debt instrument, participation lieu payments							1,000,000
Payment for debt extinguishment cost							8,000,000
Gain (loss) on restructuring of debt							$ 68,478,000
Senior Secured Term Loan | Secured Debt | Forecast | Insurer Letter Agreement
Debt Instrument [Line Items]
Payment for debt extinguishment cost	$ 4,000,000		$ 3,000,000
Senior Secured Term Loan | SOFR Loans
Debt Instrument [Line Items]
Variable rate spread								8.50%
Senior Secured Term Loan | ABR Loans
Debt Instrument [Line Items]
Stated interest rate								7.50%
Equipment financing facility
Debt Instrument [Line Items]
Non-cash interest expense - related party									178,000	292,000			387,000		609,000
Long-term line of credit						4,109,000			4,109,000				4,109,000	5,710,000		5,710,000
Long-term debt, current						3,041,000			3,041,000				3,041,000	3,332,000		3,332,000
Equipment financing facility | Line of Credit
Debt Instrument [Line Items]
Line of credit facility borrowing capacity																			$ 25,000,000
Principal						$ 4,114,000			$ 4,114,000				$ 4,114,000	5,718,000		5,718,000
Yorkville Convertible Promissory Note | Convertible Notes | Related Party
Debt Instrument [Line Items]
Proceeds from issuance of convertible notes - related party												$ 37,000,000
Amortization of debt discount										10,620,000					$ 17,572,000
Converted instrument, shares issued (in shares) | shares															22,947,029
Gain (loss) on debt extinguishment										(1,876,000)					$ (3,510,000)
Principal														$ 0		$ 0
Embedded Derivatives - Yorkville Convertible Promissory Notes | Convertible Notes | Related Party
Debt Instrument [Line Items]
Amortization of debt discount										$ (8,818,000)					$ (6,922,000)