Related Party Transactions - Narrative (Details) - USD ($)	1 Months Ended	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2024	Mar. 31, 2023
Related Party Transaction [Line Items]
Revenues		$ 3,811,000,000	$ 3,343,000,000
Related party tax payment		$ 0	0
Line of Credit | General Motors | Five Year Revolving Credit Facility
Related Party Transaction [Line Items]
Debt instrument term		5 years
Current borrowing capacity	$ 10,000,000,000	$ 10,000,000,000
Line of Credit | General Motors | 364 Day Revolving Credit Facilities
Related Party Transaction [Line Items]
Debt instrument term	364 days
Revolving Credit Facility
Related Party Transaction [Line Items]
Maximum borrowing capacity	$ 2,400,000,000	2,400,000,000
Revolving Credit Facility | Line of Credit | Cruise
Related Party Transaction [Line Items]
Maximum borrowing capacity	3,400,000,000	3,400,000,000
Revolving Credit Facility | Line of Credit | General Motors
Related Party Transaction [Line Items]
Maximum borrowing capacity	14,100,000,000	$ 14,100,000,000
Revolving Credit Facility | Line of Credit | General Motors | 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 | Line of Credit | General Motors | 364 Day Revolving Credit Facilities
Related Party Transaction [Line Items]
Maximum borrowing capacity	2,000,000,000	$ 2,000,000,000
Debt instrument term		364 days
Junior Subordinated Revolving Credit Facility | General Motors
Related Party Transaction [Line Items]
Line of credit facilities - GM Related party facility	$ 1,000,000,000	$ 1,000,000,000
GM
Related Party Transaction [Line Items]
Revenues		$ 777,000,000	$ 749,000,000