Customer Deposits (Details 1) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
U.S. retail deposits:
Savings accounts – Direct	$ 66,823	$ 63,512
Certificates of deposit:
Direct	2,211	2,440
Third-party (brokered)	5,005	5,561
Sweep accounts – Third-party (brokered)	14,049	14,070
Other deposits:
U.S. non-interest bearing deposits	22	23
Non-U.S. deposits	22	22
Card Member credit balances ― U.S. and non-U.S.	1,061	1,247
Total customer deposits	$ 89,193	$ 86,875