Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Non Interest Revenues [Abstract]
Other		$ 874	$ 1,430	$ 1,360
Total non-interest revenues		28,102	34,936	32,675
Interest income
Interest on loans		9,779	11,308	9,941
Interest and dividends on investment securities		127	188	118
Deposits with banks and other		177	588	547
Total interest income		10,083	12,084	10,606
Interest expense
Deposits		943	1,559	1,287
Long-term debt and other		1,155	1,905	1,656
Total interest expense		2,098	3,464	2,943
Net interest income		7,985	8,620	7,663
Total revenues net of interest expense		36,087	43,556	40,338
Provisions for credit losses
Provisions for credit losses		4,730	3,573	3,352
Total revenues net of interest expense after provisions for credit losses		31,357	39,983	36,986
Expenses
Marketing and business development		6,747	7,125	6,477
Card Member rewards		8,041	10,439	9,696
Card Member services		1,230	2,223	1,777
Salaries and employee benefits		5,718	5,911	5,250
Other, net		5,325	5,856	5,664
Total expenses		27,061	31,554	28,864
Pretax income		4,296	8,429	8,122
Income tax provision		1,161	1,670	1,201
Net income		$ 3,135	$ 6,759	$ 6,921
Earnings per Common Share
Basic (in dollars per share)	[1]	$ 3.77	$ 8.00	$ 7.93
Diluted (in dollars per share)	[1]	$ 3.77	$ 7.99	$ 7.91
Average common shares outstanding for earnings per common share:
Basic (in shares)		805	828	856
Diluted (in shares)		806	830	859
Card Member Receivables [Member]
Provisions for credit losses
Provisions for credit losses		$ 1,015	$ 963	$ 937
Card Member Loans [Member]
Provisions for credit losses
Provisions for credit losses		3,453	2,462	2,266
Other Loans [Member]
Provisions for credit losses
Provisions for credit losses		262	148	149
Discount Revenue [Member]
Non Interest Revenues [Abstract]
Revenues, fees, and commissions		20,401	26,167	24,721
Net Card Fees [Member]
Non Interest Revenues [Abstract]
Revenues, fees, and commissions		4,664	4,042	3,441
Other Fees and Commissions [Member]
Non Interest Revenues [Abstract]
Revenues, fees, and commissions		$ 2,163	$ 3,297	$ 3,153

[1] Represents net income less (i) earnings allocated to participating share awards of $20 million, $47 million and $54 million for the years ended December 31, 2020, 2019 and 2018, respectively, and (ii) dividends on preferred shares of $79 million, $81 million and $80 million for the years ended December 31, 2020, 2019 and 2018, respectively.