Customer Deposits - Categorized as Interest or Non-interest Bearing (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
U.S.:
Interest-bearing	$ 123,510	$ 109,119
Non-interest-bearing (includes Card Member credit balances of: 2023, $442; 2022, $605)	492	663
Non-U.S.:
Interest-bearing	14	15
Non-interest-bearing (includes Card Member credit balances of: 2023, $420; 2022, $439)	423	442
Total customer deposits	124,439	110,239
Card Member Credit Balances
U.S.:
Non-interest-bearing (includes Card Member credit balances of: 2023, $442; 2022, $605)	442	605
Non-U.S.:
Non-interest-bearing (includes Card Member credit balances of: 2023, $420; 2022, $439)	$ 420	$ 439