v3.25.4
Summary of Significant Accounting Policies - Narrative (Details)
 12 Months Ended
Dec. 31, 2025
USD ($)
platform
Dec. 31, 2024
USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]    
Government assistance, award amount $ 14,800,000  
Government assistance, nonoperating income, $ 400,000  
Government Assistance, Nonoperating Income, Increase (Decrease), Statement of Income or Comprehensive Income [Extensible Enumeration] Nonoperating Income (Expense)  
Government grant receivable $ 0  
Deferred grant $ 2,738,000 $ 0
Number of primary battery platforms | platform 1  
Restricted cash and cash equivalents included in prepaid expenses and other current assets $ 200,000  
Restricted cash and cash equivalents included in other assets   1,300,000
Accounts receivable allowance for credit loss 500,000 0
Impairment loss 19,100,000 0
ROU asset impairment 14,400,000  
Other long-lived assets impairment charges 4,700,000  
Impairment and other 22,524,000 1,862,000
Loss on retirement of production equipment 3,500,000 1,900,000
Product warranty liability 0 0
Revenue 73,011,000 24,167,000
UKRAINE    
New Accounting Pronouncements or Change in Accounting Principle [Line Items]    
Revenue $ 33,000,000.0 6,400,000
Customer one | Accounts receivable | Customer concentration risk    
New Accounting Pronouncements or Change in Accounting Principle [Line Items]    
Concentration risk percentage 64.00%  
Customer one | Revenue benchmark | Customer concentration risk    
New Accounting Pronouncements or Change in Accounting Principle [Line Items]    
Revenue $ 27,100,000 $ 5,400,000
Customer two | Accounts receivable | Customer concentration risk    
New Accounting Pronouncements or Change in Accounting Principle [Line Items]    
Concentration risk percentage   50.00%
Customer two | Revenue benchmark | Customer concentration risk    
New Accounting Pronouncements or Change in Accounting Principle [Line Items]    
Revenue   $ 2,800,000
Customer three | Revenue benchmark | Customer concentration risk    
New Accounting Pronouncements or Change in Accounting Principle [Line Items]    
Revenue   2,800,000
Money market funds | Level 1    
New Accounting Pronouncements or Change in Accounting Principle [Line Items]    
Cash equivalents $ 27,000,000.0 $ 23,500,000
Stock options | Equity Incentive Plans    
New Accounting Pronouncements or Change in Accounting Principle [Line Items]    
Award vesting period (in years) 4 years  
RSUs | Equity Incentive Plans    
New Accounting Pronouncements or Change in Accounting Principle [Line Items]    
Award vesting period (in years) 4 years