Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2018		Jun. 30, 2017		Jun. 30, 2018		Jun. 30, 2017
Non-interest revenues
Discount revenue	$ 6,194		$ 5,743		$ 12,083		$ 11,130
Net card fees	844		771		1,674		1,519
Other fees and commissions	786		746		1,567		1,457
Other	349		379		726		740
Total non-interest revenues	8,173		7,639		16,050		14,846
Interest income
Interest on loans	2,387		1,950		4,713		3,812
Interest and dividends on investment securities	27		23		48		46
Deposits with banks and other	126		81		241		141
Total interest income	2,540		2,054		5,002		3,999
Interest expense
Deposits	300		176		570		325
Long-term debt and other	411		345		762		639
Total interest expense	711		521		1,332		964
Net interest income	1,829		1,533		3,670		3,035
Total revenues net of interest expense	10,002		9,172		19,720		17,881
Provisions for losses
Charge card	245		163		487		376
Card Member loans	528		404		1,027		741
Other	33		16		67		39
Total provisions for losses	806		583		1,581		1,156
Total revenues net of interest expense after provisions for losses	9,196		8,589		18,139		16,725
Expenses
Marketing and business development	1,663		1,456		3,008		2,741
Card Member rewards	2,433		2,196		4,780		4,257
Card Member services	416		341		825		658
Salaries and employee benefits	1,280		1,293		2,606		2,557
Other, net	1,313		1,346		2,747		2,716
Total expenses	7,105		6,632		13,966		12,929
Pretax income	2,091		1,957		4,173		3,796
Income tax provision	468		613		916		1,201
Net income	$ 1,623		$ 1,344		$ 3,257		$ 2,595
Earnings Per Common Share, Basic (Note 15) [Abstract]
Net income attributable to common shareholders	$ 1.85	[1]	$ 1.48	[1]	$ 3.71	[2]	$ 2.83	[2]
Earnings Per Common Share, Diluted (Note 15) [Abstract]
Net income attributable to common shareholders	$ 1.84	[1]	$ 1.47	[1]	$ 3.7	[2]	$ 2.82	[2]
Average common shares outstanding for earnings per common share:
Basic	860		890		859		895
Diluted	862		893		862		898
Cash dividends declared per common share	$ 0.35		$ 0.32		$ 0.7		$ 0.64

[1] Rep resents net income less (i) earnings allocated to participating share awards of $ 12 million and $ 11 million for the three months ended June 30 , 2018 and 2017 , respectively, and (ii) dividends on preferred shares of $ 20 million and $ 19 million for the three months ended June 30 , 2018 and 2017 , respectively .

[2] Represents net income less (i) earnings allocated to participating share awards of $ 25 million and $ 21 million for the six months ended June 30 , 2018 and 2017 , respectively, and (ii) dividends on preferred shares of $ 41 million and $ 40 million for the six months ended June 30 , 2018 and 2017 , respectively .