Debt (Details 1) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term Debt	$ 55,804	$ 46,990
Unamortized Underwriting Fees	$ (111)	$ (71)
Long-term Debt [Member]
Debt Instrument [Line Items]
Year-End Stated Rate on Debt	2.44%	2.39%
Parent Company [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 12,695	$ 8,364
Fixed Rate Senior Notes Amount [Member] | Parent Company [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 10,377	$ 6,932
Year-End Effective Interest Rates with Swaps	3.17%	4.24%
Fixed Rate Senior Notes Amount [Member] | Parent Company [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Year-End Stated Rate on Debt	3.85%	5.13%
Fixed Rate Senior Notes Amount [Member] | American Express Centurion Bank [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 0	$ 1,306
Year-End Effective Interest Rates with Swaps	0.00%	4.83%
Fixed Rate Senior Notes Amount [Member] | American Express Centurion Bank [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Year-End Stated Rate on Debt	0.00%	5.99%
Fixed Rate Senior Notes Amount [Member] | American Express Credit Corporation [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 19,652	$ 16,201
Year-End Effective Interest Rates with Swaps	2.27%	1.44%
Fixed Rate Senior Notes Amount [Member] | American Express Credit Corporation [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Year-End Stated Rate on Debt	2.24%	1.98%
Fixed Rate Senior Notes Amount [Member] | American Express Bank, FSB [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 0	$ 1,000
Year-End Effective Interest Rates with Swaps	0.00%	0.00%
Fixed Rate Senior Notes Amount [Member] | American Express Bank, FSB [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Year-End Stated Rate on Debt	0.00%	6.00%
Fixed Rate Senior Notes Amount [Member] | American Express Lending Trust [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 8,099	$ 3,500
Year-End Effective Interest Rates with Swaps	0.00%	0.00%
Fixed Rate Senior Notes Amount [Member] | American Express Lending Trust [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Year-End Stated Rate on Debt	1.90%	1.41%
Floating Rate Senior Notes Amount [Member] | Parent Company [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 1,750	$ 850
Year-End Effective Interest Rates with Swaps	0.00%	0.00%
Floating Rate Senior Notes Amount [Member] | Parent Company [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Year-End Stated Rate on Debt	1.93%	1.51%
Floating Rate Senior Notes Amount [Member] | American Express Centurion Bank [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 125	$ 125
Year-End Effective Interest Rates with Swaps	0.00%	0.00%
Floating Rate Senior Notes Amount [Member] | American Express Centurion Bank [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Year-End Stated Rate on Debt	1.89%	1.26%
Floating Rate Senior Notes Amount [Member] | American Express Credit Corporation [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 4,550	$ 4,350
Year-End Effective Interest Rates with Swaps	0.00%	0.00%
Floating Rate Senior Notes Amount [Member] | American Express Credit Corporation [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Year-End Stated Rate on Debt	2.09%	1.52%
Floating Rate Senior Notes Amount [Member] | American Express Bank, FSB [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 0	$ 300
Year-End Effective Interest Rates with Swaps	0.00%	0.00%
Floating Rate Senior Notes Amount [Member] | American Express Bank, FSB [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Year-End Stated Rate on Debt	0.00%	0.96%
Floating Rate Senior Notes Amount [Member] | American Express Charge Trust II [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 4,200	$ 4,200
Year-End Effective Interest Rates with Swaps	0.00%	0.00%
Floating Rate Senior Notes Amount [Member] | American Express Charge Trust II [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Year-End Stated Rate on Debt	1.79%	1.12%
Floating Rate Senior Notes Amount [Member] | American Express Lending Trust [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 5,800	$ 7,025
Year-End Effective Interest Rates with Swaps	0.00%	0.00%
Floating Rate Senior Notes Amount [Member] | American Express Lending Trust [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Year-End Stated Rate on Debt	2.03%	1.20%
Floating Rate Subordinated Notes Amount [Member] | American Express Charge Trust II [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 87	$ 87
Year-End Effective Interest Rates with Swaps	0.00%	0.00%
Floating Rate Subordinated Notes Amount [Member] | American Express Charge Trust II [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Year-End Stated Rate on Debt	2.11%	1.34%
Floating Rate Subordinated Notes Amount [Member] | American Express Lending Trust [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 192	$ 316
Year-End Effective Interest Rates with Swaps	0.00%	0.00%
Floating Rate Subordinated Notes Amount [Member] | American Express Lending Trust [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Year-End Stated Rate on Debt	2.05%	1.34%
Convertible Subordinated Debt [Member] | Parent Company [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 598	$ 598
Year-End Effective Interest Rates with Swaps	2.66%	1.92%
Convertible Subordinated Debt [Member] | Parent Company [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Year-End Stated Rate on Debt	3.63%	3.63%
Borrowings under Bank Credit Facilities [Member] | American Express Credit Corporation [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 0	$ 0
Year-End Effective Interest Rates with Swaps	0.00%	0.00%
Borrowings under Bank Credit Facilities [Member] | American Express Credit Corporation [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Year-End Stated Rate on Debt	0.00%	0.00%
Fixed Rate Subordinated Notes Amount [Member] | American Express Lending Trust [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 206	$ 0
Year-End Stated Rate on Debt	2.21%
Year-End Effective Interest Rates with Swaps	0.00%	0.00%
Fixed Rate Subordinated Notes Amount [Member] | American Express Lending Trust [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Year-End Stated Rate on Debt	0.00%	0.00%
Fixed Rate Instruments [Member] | Other Subsidiaries [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 23	$ 24
Year-End Effective Interest Rates with Swaps	0.00%	0.00%
Fixed Rate Instruments [Member] | Other Subsidiaries [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Year-End Stated Rate on Debt	5.59%	5.62%
Fixed Rate Instruments [Member] | Other Subsidiaries [Member] | Capitalized lease transactions
Debt Instrument [Line Items]
Long-term Debt	$ 23	$ 24
Floating Rate Borrowings [Member] | Other Subsidiaries [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 256	$ 247
Year-End Effective Interest Rates with Swaps	0.00%	0.00%
Floating Rate Borrowings [Member] | Other Subsidiaries [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Year-End Stated Rate on Debt	0.42%	0.44%