Transactions with Affiliates 2 (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Short-term debt to affiliates	$ 5,899	$ 5,997	$ 4,559
AE Exposure Management Limited [Member]
Related Party Transaction [Line Items]
Short-term debt to affiliates	5,122	4,548
American Express Swiss Holdings Gmbh [Member]
Related Party Transaction [Line Items]
Short-term debt to affiliates	0	444
American Express Europe LLC [Member]
Related Party Transaction [Line Items]
Short-term debt to affiliates	517	765
American Express Holdings Netherlands CV [Member]
Related Party Transaction [Line Items]
Short-term debt to affiliates	192	192
Accertify Inc. [Member]
Related Party Transaction [Line Items]
Short-term debt to affiliates	$ 68	$ 48