Transactions with Affiliates 1 (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Loans to affiliates and other	$ 10,345	$ 14,136	$ 14,527
American Express Services Europe Limited [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	4,206	3,552
American Express Australia Limited [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	2,052	1,839
Amex Bank of Canada [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	1,587	1,334
Amex Global Holdings CV [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	888	888
American Express Company (Mexico) S.A. de C.V. [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	534	463
American Express International, Inc. - Branch - Singapore [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	413	383
American Express Bank (Mexico) S.A. [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	404	348
Alpha Card S.C.R.L./C.V.B.A [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	120	114
American Express Saudi Arabia (C) JSC [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	71	53
American Express International (NZ), Inc. [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	70	72
American Express Limited [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	0	3,847
American Express International, Inc. [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	$ 0	$ 1,243