Parent Company (Details 2) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Flows from Operating Activities
Net income (loss)	$ 1,438	$ 1,073	$ 257	$ 367	$ 1,693	$ 1,755	$ 1,761	$ 1,550	$ 3,135	$ 6,759	$ 6,921
Adjustments to reconcile net income to net cash provided by operating activities:
Net cash provided by operating activities									5,591	13,632	8,930
Cash Flows from Investing Activities
Purchase of investments									(20,562)	(11,166)	(5,434)
Maturities and redemptions of investment securities									7,159	7,329	3,499
Other investing activities									135	152	0
Net cash provided by (used in) investing activities									11,632	(16,707)	(19,615)
Cash Flows from Financing Activities
Proceeds from long-term borrowings									69	12,706	21,524
Payments of long-term debt									(15,593)	(13,850)	(18,895)
Issuance of American Express common shares and other									44	86	87
Dividends paid									(1,474)	(1,422)	(1,324)
Net cash (used in) provided by financing activities									(9,068)	(519)	5,101
Net increase (decrease) in cash and cash equivalents									8,519	(3,362)	(5,455)
Cash. cash equivalents and restricted cash at beginning of year				24,446				27,808	24,446	27,808	33,263
Cash, cash equivalents and restricted cash at end of year	32,965				24,446				32,965	24,446	27,808
Parent Company [Member]
Cash Flows from Operating Activities
Net income (loss)									3,135	6,759	6,921
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in net income of subsidiaries and affiliates									(3,716)	(7,271)	(7,452)
Dividends received from subsidiaries and affiliates									2,679	6,370	3,222
Other operating activities, primarily with subsidiaries and affiliates									732	1,315	(257)
Net cash provided by operating activities									2,830	7,173	2,434
Cash Flows from Investing Activities
Maturities and redemptions of investment securities									0	1	0
Loans to subsidiaries and affiliates									11,434	(4,405)	(6,281)
Investments in subsidiaries and affiliates									(52)	(15)	(30)
Other investing activities									74	82	0
Net cash provided by (used in) investing activities									11,456	(4,337)	(6,311)
Cash Flows from Financing Activities
Proceeds from long-term borrowings									0	6,469	9,350
Payments of long-term debt									(2,000)	(641)	(3,850)
Short-term debt of subsidiaries and affiliates									(3,289)	(1,500)	(140)
Issuance of American Express common shares and other									44	86	87
Repurchase of American Express common shares									(1,029)	(4,685)	(1,685)
Dividends paid									(1,474)	(1,422)	(1,324)
Net cash (used in) provided by financing activities									(7,748)	(1,693)	2,438
Net increase (decrease) in cash and cash equivalents									6,538	1,143	(1,439)
Cash. cash equivalents and restricted cash at beginning of year				$ 4,430				$ 3,287	4,430	3,287	4,726
Cash, cash equivalents and restricted cash at end of year	$ 10,968				$ 4,430				10,968	4,430	3,287
Non-Cash Investing Activities
Loans to subsidiaries and affiliates									(4,971)	0	0
Non-Cash Financing Activities
Short-term debts from subsidiaries and affiliates									$ 4,971	$ 0	$ 0