Transactions with Affiliates (Details 1) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Related Party Transaction [Line Items]
Loans to affiliates and other	$ 14,527	$ 10,659	$ 14,262
American Express Company [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	961	4,044
American Express Services Europe Limited [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	2,747	2,484
Amex Bank Of Canada [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	1,737	1,593
American Express Australia Limited [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	1,616	1,290
American Express Company (Mexico) S.A. de C.V. [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	812	765
American Express Bank (Mexico) S.A. [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	325	291
American Express International, Inc. [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	1,180	0
American Express Saudi Arabia (C) JSC [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	34	0
Alpha Card S.C.R.L./C.V.B.A [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	138	0
American Express International (NZ), Inc. [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	80	85
American Express Limited [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	3,847	0
Amex Global Holdings CV [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	888	0
Amex Funding Management (Europe) Limited [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	38	0
American Express International, Inc. - Branch - Singapore [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	$ 124	$ 107