Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2017		Sep. 30, 2016		Sep. 30, 2017		Sep. 30, 2016
Non-interest revenues
Discount revenue	$ 4,772		$ 4,516		$ 14,106		$ 13,983
Net card fees	786		747		2,305		2,161
Other fees and commissions	767		694		2,232		2,076
Other	436		483		1,284		1,514
Total non-interest revenues	6,761		6,440		19,927		19,734
Interest income
Interest on loans	2,129		1,690		5,936		5,446
Interest and dividends on investment securities	22		34		68		104
Deposits with banks and other	91		40		233		104
Total interest income	2,242		1,764		6,237		5,654
Interest expense
Deposits	213		150		538		450
Long-term debt and other	354		280		994		841
Total interest expense	567		430		1,532		1,291
Net interest income	1,675		1,334		4,705		4,363
Total revenues net of interest expense	8,436		7,774		24,632		24,097
Provisions for losses
Charge card	214		174		590		496
Card Member loans	531		319		1,272		831
Other	24		11		64		74
Total provisions for losses	769		504		1,926		1,401
Total revenues net of interest expense after provisions for losses	7,667		7,270		22,706		22,696
Expenses
Marketing and promotion	814		930		2,344		2,445
Card Member Rewards	1,900		1,566		5,633		5,035
Card Member services and other	363		278		1,033		841
Salaries and employee benefits	1,265		1,263		3,822		4,052
Other, net	1,498		1,498		4,281		3,388
Total expenses	5,840		5,535		17,113		15,761
Pretax income	1,827		1,735		5,593		6,935
Income tax provision	471		593		1,660		2,352
Net income	$ 1,356		$ 1,142		$ 3,933		$ 4,583
Earnings Per Common Share, Basic (Note 15) [Abstract]
Net income attributable to common shareholders	$ 1.51	[1]	$ 1.21	[1]	$ 4.32	[2]	$ 4.77	[2]
Earnings Per Common Share, Diluted (Note 15) [Abstract]
Net income attributable to common shareholders	$ 1.5	[1]	$ 1.2	[1]	$ 4.3	[2]	$ 4.76	[2]
Average common shares outstanding for earnings per common share:
Basic	878		920		889		940
Diluted	881		923		892		943
Cash dividends declared per common share	$ 0.35		$ 0.32		$ 0.99		$ 0.9

[1] Represents net income less (i) earnings allocated to participating share awards of $ 11 million and $ 9 million for the three months ended September 30 , 2017 and 2016 , respectively, and (ii) dividends on preferred shares of $ 21 million for both the three months ended September 30 , 2017 and 2016 .

[2] Represents net income less (i) earnings allocated to participating share awards of $ 32 million and $ 37 million for the nine months ended September 30 , 2017 and 2016 , respectively, and (ii) dividends on preferred shares of $ 61 million for both the nine months ended September 30 , 2017 and 2016 .