v3.26.3
Related Party Transactions - Narrative (Details) - USD ($)
1 Months Ended 3 Months Ended 9 Months Ended
Mar. 31, 2026
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Related Party Transaction [Line Items]          
Revenues   $ 4,312,000,000 $ 4,337,000,000 $ 12,854,000,000 $ 12,755,000,000
Related party tax payment       $ 158,000,000 0
General Motors | Line of Credit | Five Year Revolving Credit Facility          
Related Party Transaction [Line Items]          
Debt instrument term       5 years  
Current borrowing capacity   10,000,000,000.0   $ 10,000,000,000.0  
Junior Subordinated Revolving Credit Facility | General Motors          
Related Party Transaction [Line Items]          
Line of credit facilities - GM related party facility   1,000,000,000.0   1,000,000,000.0  
Revolving Credit Facility | General Motors | Line of Credit          
Related Party Transaction [Line Items]          
Maximum borrowing capacity   14,100,000,000   $ 14,100,000,000  
Revolving Credit Facility | General Motors | Line of Credit | Three Year Revolving Credit Facility          
Related Party Transaction [Line Items]          
Debt instrument term       3 years  
Current borrowing capacity   4,100,000,000   $ 4,100,000,000  
Revolving Credit Facility | General Motors | Line of Credit | 364 Day Revolving Credit Facilities          
Related Party Transaction [Line Items]          
Maximum borrowing capacity   2,000,000,000.0   $ 2,000,000,000.0  
Debt instrument term 364 days     364 days  
GM          
Related Party Transaction [Line Items]          
Revenues   $ 796,000,000 $ 856,000,000 $ 2,100,000,000 $ 2,500,000,000