Borrowings - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
2021 Convertible Note Payable | Convertible Notes
Debt Instrument [Line Items]
Contractual interest expense	$ 1,843	$ 1,737
Amortization of debt discount	1,915	1,531
Amortization of debt issuance costs	184	148
Total	3,942	3,416
DOE Loan Facility | Line of Credit
Debt Instrument [Line Items]
Contractual interest expense	808
Amortization of debt issuance costs	91
Total	899
AFG Convertible Notes | Convertible Notes | Related Party
Debt Instrument [Line Items]
Contractual interest expense	1,481	1,155
Amortization of debt discount	279	218
Amortization of debt issuance costs	79	62
Total	1,839	1,435
Senior Secured Term Loan | Secured Debt | Nonrelated Party
Debt Instrument [Line Items]
Contractual interest expense	0	3,684
Amortization of debt discount	0	115
Amortization of debt issuance costs	0	1,017
Total	$ 0	$ 4,816