Customer Deposits (Details 1) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
U.S. retail deposits:
Savings accounts - Direct	$ 60,370	$ 46,394
Certificates of deposit - Direct	2,592	1,854
Certificates of deposit - Third party	6,899	8,076
Sweep accounts - Third party	14,102	16,121
Other deposits:
U.S. non-interest bearing deposits, Other	25	26
Non-US Deposits, Other	23	26
Card Member credit balances - U.S. and non-U.S.	1,450	790
Total customer deposits	$ 85,461	$ 73,287