Summary of Significant Accounting Policies - Card Member Loans HFS (Details) - USD ($) $ in Millions		12 Months Ended
	Dec. 01, 2024	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Reversal of reserve for credit losses		$ (5,185)	$ (4,923)	$ (2,182)
Card Member loans
Disaggregation of Revenue [Line Items]
Financing receivables held for sale	$ 758	758	0
Reversal of reserve for credit losses	$ 49	$ (4,109)	$ (3,839)	$ (1,514)