Customer Deposits - By Deposit Type (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
U.S. interest-bearing deposits:
Savings accounts	$ 113,243	$ 108,364
Checking accounts	2,324	2,045
Certificates of deposit:
Direct	4,291	4,303
Third-party (brokered)	10,117	8,109
Sweep accounts – Third-party (brokered)	15,519	15,612
Total U.S. interest-bearing deposits	145,494	138,433
Other deposits	81	72
Total customer deposits	146,396	139,413
Card Member Credit Balances
Certificates of deposit:
Card Member credit balances	$ 821	$ 908