Customer Deposits (Details 1) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
U.S. retail deposits:
Savings accounts – Direct	$ 65,721	$ 63,512
Certificates of deposit:
Direct	1,665	2,440
Third-party (brokered)	3,274	5,561
Sweep accounts – Third-party (brokered)	12,637	14,070
Other deposits:
U.S. deposits	24	23
Non-U.S. deposits	23	22
Card Member credit balances ― U.S. and non-U.S.	982	1,247
Total customer deposits	$ 84,326	$ 86,875