Customer Deposits (Details 1) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
U.S. retail deposits:
Savings accounts - Direct	$ 48,981	$ 46,394
Certificates of deposit - Direct	2,360	1,854
Certificates of deposit - Third party	8,715	8,076
Sweep accounts - Third party	16,403	16,121
Other deposits:
U.S. non-interest bearing deposits, Other	24	26
Non-US Deposits, Other	27	26
Card Member credit balances - U.S. and non-U.S.	1,452	790
Total customer deposits	$ 77,962	$ 73,287