Customer Deposits (Details 1) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
U.S. retail deposits:
Savings accounts - Direct	$ 44,989	$ 39,491
Certificates of deposit - Direct	1,757	817
Certificates of deposit - Third party	9,598	12,667
Sweep accounts - Third party	16,191	16,169
Other deposits:
U.S. non-interest bearing deposits, Other	29	36
Non-US Deposits, Other	29	37
Card Member credit balances - U.S. and non-U.S.	705	743
Total customer deposits	$ 73,298	$ 69,960