Equity in Net Assets of Non-consolidated Affiliates (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Noncontrolling Interest [Line Items]
Finance charge income		$ 1,062	$ 1,036	$ 2,072	$ 2,052
Income before income taxes		1,106	1,581	2,390	2,763
Net income		50	50	104	104
Joint Ventures
Noncontrolling Interest [Line Items]
Finance charge income		424	418	875	848
Income before income taxes		190	191	396	394
Net income		143	$ 143	297	$ 296
Undistributed earnings	$ 845	$ 845		$ 845		$ 740
SAIC-GMAC
Noncontrolling Interest [Line Items]
Cash dividends received	$ 26