Transactions with Affiliates 2 (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Short-term debt to affiliates	$ 8,569	$ 6,225	$ 5,899
American Express Travel Related Services Company, Inc. [Member]
Related Party Transaction [Line Items]
Short-term debt to affiliates	7,073	0
AE Exposure Management Limited [Member]
Related Party Transaction [Line Items]
Short-term debt to affiliates	1,193	5,731
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	107	82
American Express Swiss Holdings Gmbh [Member]
Related Party Transaction [Line Items]
Short-term debt to affiliates	4	1
American Express Europe LLC [Member]
Related Party Transaction [Line Items]
Short-term debt to affiliates	$ 0	$ 219