Transactions with Affiliates 1 (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Loans to affiliates and other	$ 10,890	$ 10,345	$ 14,136
Collateralized [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	6,400	8,200
American Express Services Europe Limited [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	2,881	4,206
American Express Company [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	2,772	0
American Express Australia Limited [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	1,745	2,052
Amex Global Holdings CV [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	1,430	888
Amex Bank of Canada [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	857	1,587
American Express Company (Mexico) S.A. de C.V. [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	540	534
American Express International, Inc. - Branch - Singapore [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	303	413
American Express Bank (Mexico) S.A. [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	257	404
American Express International (NZ), Inc. [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	56	70
Alpha Card S.C.R.L./C.V.B.A [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	25	120
American Express Saudi Arabia (C) JSC [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	$ 24	$ 71