Variable Interest Entity (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Total assets	$ 36,938	$ 31,936
Total liabilities	34,168	29,727
Variable Interest Entity, Primary Beneficiary [Member] | American Express Canada Credit Corporation Member [Member]
Variable Interest Entity [Line Items]
Total assets	1,900	1,700
Total liabilities	1,900	1,700
Liabilities eliminated in consolidation	$ 1,400	$ 1,300