Parent Company (Details 2) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flows from Operating Activities
Net income	$ 2,010	$ 1,654	$ 1,623	$ 1,634	$ (1,206)	$ 1,359	$ 1,344	$ 1,251	$ 6,921	$ 2,748	$ 5,375
Adjustments to reconcile income from continuing operations to net cash provided by operating activities:
Premium paid on debt exchange									0	0	0
Net cash provided by operating activities									8,930	13,540	8,291
Cash Flows from Investing Activities
Purchase of investments									(5,434)	(2,612)	(2,162)
Purchase of premises and equipment									(1,310)	(1,062)	(1,375)
Net cash (used in) provided by investing activities									(19,615)	(18,242)	1,723
Cash Flows from Financing Activities
Proceeds from long-term borrowings									21,524	32,764	8,824
Principal payments on long term debt									(18,895)	(24,082)	(9,848)
Issuance of American Express common shares and other									87	129	177
Repurchase of American Express common shares									(1,600)	(4,300)	(4,400)
Dividends paid									(1,324)	(1,251)	(1,207)
Net cash provided by (used in) financing activities									5,101	12,245	(7,599)
Net increase (decrease) in cash and cash equivalents									(5,455)	7,769	2,255
Cash and cash equivalents at beginning of year				32,927				25,208	32,927	25,208	23,239
Cash and cash equivalents at end of year	27,445				32,927				27,445	32,927	25,208
Parent Company [Member]
Cash Flows from Operating Activities
Net income									6,921	2,748	5,375
Adjustments to reconcile income from continuing operations to net cash provided by operating activities:
Equity in net income of subsidiaries and affiliates									(7,452)	(3,186)	(5,870)
Dividends received from subsidiaries and affiliates									3,222	5,755	4,999
Other operating activities, primarily with subsidiaries and affiliates									(257)	659	(102)
Net cash provided by operating activities									2,434	5,976	4,402
Cash Flows from Investing Activities
Purchase of premises and equipment									0	0	(1)
Loans to subsidiaries and affiliates									(6,281)	(4,044)	4,142
Investments In Subsidiaries And Affiliates									(30)	0	(25)
Net cash (used in) provided by investing activities									(6,311)	(4,044)	4,116
Cash Flows from Financing Activities
Proceeds from long-term borrowings									9,350	5,900	0
Principal payments on long term debt									(3,850)	(1,500)	(1,350)
Short-term debt of subsidiaries and affiliates									(140)	(1,313)	(2,879)
Issuance of American Express common shares and other									87	129	176
Repurchase of American Express common shares									(1,685)	(4,400)	(4,430)
Dividends paid									(1,324)	(1,251)	(1,206)
Net cash provided by (used in) financing activities									2,438	(2,435)	(9,689)
Net increase (decrease) in cash and cash equivalents									(1,439)	(503)	(1,171)
Cash and cash equivalents at beginning of year				$ 4,726				$ 5,229	4,726	5,229	6,400
Cash and cash equivalents at end of year	$ 3,287				$ 4,726				$ 3,287	$ 4,726	$ 5,229