Customer Deposits - By Deposit Type (Details) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
U.S. interest-bearing deposits:
Savings accounts	$ 118,337	$ 116,867
Checking accounts	3,801	2,965
Certificates of deposit:
Direct	9,882	5,979
Third-party (brokered)	8,853	9,919
Sweep accounts – Third-party (brokered)	13,053	15,696
Total U.S. interest-bearing deposits	153,926	151,425
Other deposits	85	71
Total customer deposits	155,019	152,488
Card Member Credit Balances
Certificates of deposit:
Card Member credit balances	$ 1,008	$ 992