Customer Deposits (Details 1) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
U.S. retail deposits:
Savings accounts - Direct	$ 43,345	$ 39,491
Certificates of deposit - Direct	1,107	817
Certificates of deposit - Third party	12,189	12,667
Sweep accounts - Third party	15,469	16,169
Other retail deposits:
U.S. non-interest bearing deposits, Other	34	36
Non-US Deposits, Other	36	37
Card Member credit balances - U.S. and non-U.S.	677	743
Total customer deposits	$ 72,857	$ 69,960