Customer Deposits (Details 1) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
U.S. retail deposits:
Savings accounts - Direct	$ 30,276	$ 30,980
Certificates of deposit - Direct	285	291
Certificates of deposit - Third party	14,997	11,925
Sweep accounts - Third party	11,454	9,120
Other retail deposits:
Non-U.S. deposits and U.S. non-interest bearing deposits	80	110
Card Member credit balances - U.S. and non-U.S.	634	616
Total customer deposits	$ 57,726	$ 53,042