Transactions with Affiliates (Details 2) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Related Party Transaction [Line Items]
Short-term debt to affiliates	$ 5,997	$ 4,559	$ 5,439
AE Exposure Management Limited [Member]
Related Party Transaction [Line Items]
Short-term debt to affiliates	4,548	3,361
American Express Swiss Holdings Gmbh [Member]
Related Party Transaction [Line Items]
Short-term debt to affiliates	444	376
American Express Europe LLC [Member]
Related Party Transaction [Line Items]
Short-term debt to affiliates	765	515
American Express Holdings Netherlands CV [Member]
Related Party Transaction [Line Items]
Short-term debt to affiliates	192	192
Amex Funding Management (Europe) Limited [Member]
Related Party Transaction [Line Items]
Short-term debt to affiliates	0	73
Accertify Inc. [Member]
Related Party Transaction [Line Items]
Short-term debt to affiliates	$ 48	$ 42