Consolidated Statements of Income (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Non-interest revenues
Discount revenue	$ 4,482	$ 4,278	$ 8,739	$ 8,180
Net card fees	615	613	1,225	1,214
Travel commissions and fees	521	523	972	977
Other commissions and fees	575	584	1,158	1,113
Other	651	537	1,231	1,012
Total non-interest revenues	6,844	6,535	13,325	12,496
Interest income
Interest and fees on loans	1,582	1,543	3,193	3,098
Interest and dividends on investment securities	67	99	133	187
Deposits with banks and other	22	18	52	38
Total interest income	1,671	1,660	3,378	3,323
Interest expense
Deposits	115	131	244	268
Short-term borrowings	6	1	11	1
Long-term debt and other	429	445	869	901
Total interest expense	550	577	1,124	1,170
Net interest income	1,121	1,083	2,254	2,153
Total revenues net of interest expense	7,965	7,618	15,579	14,649
Provisions for losses
Charge card	163	161	341	359
Cardmember loans	277	176	489	56
Other	21	20	43	39
Total provisions for losses	461	357	873	454
Total revenues net of interest expense after provisions for losses	7,504	7,261	14,706	14,195
Expenses
Marketing, promotion, rewards and cardmember services	2,415	2,581	4,734	5,031
Salaries and employee benefits	1,536	1,595	3,171	3,117
Professional services	711	745	1,402	1,408
Other, net	963	575	1,747	1,142
Total	5,625	5,496	11,054	10,698
Pretax income from continuing operations	1,879	1,765	3,652	3,497
Income tax provision	540	470	1,057	1,025
Income from continuing operations	1,339	1,295	2,595	2,472
Income from discontinued operations, net of tax	0	36	0	36
Net income	$ 1,339	$ 1,331	$ 2,595	$ 2,508
Earnings Per Share, Basic [Abstract]
Income from continuing operations attributable to common shareholders	$ 1.16	$ 1.08	$ 2.23	$ 2.05
Income from discontinued operations	$ 0	$ 0.03	$ 0	$ 0.03
Net income attributable to common shareholders	$ 1.16	$ 1.11	$ 2.23	$ 2.08
Earnings Per Share, Diluted [Abstract]
Income from continuing operations attributable to common shareholders	$ 1.15	$ 1.07	$ 2.22	$ 2.04
Income from discontinued operations	$ 0	$ 0.03	$ 0	$ 0.03
Net income attributable to common shareholders	$ 1.15	$ 1.10	$ 2.22	$ 2.07
Average common shares outstanding for earnings per common share:
Basic	1,145	1,190	1,151	1,190
Diluted	1,152	1,197	1,158	1,197
Common Stock Dividends Per Share Declared [Abstract]
Cash dividends declared per common share	$ 0.20	$ 0.18	$ 0.40	$ 0.36