Earnings Per Common Share (EPS) (Details) (USD $) In Millions, except Per Share data	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Basic and diluted:
Income from continuing operations	$ 1,235		$ 1,093		$ 3,707		$ 2,995
Earnings allocated to participating share awards and other items.	(15)		(13)		(44)		(38)
Income from discontinued operations, net of tax					36		0
Net income attributable to common shareholders	1,220		1,080		3,699		2,957
Average common shares outstanding for earnings per common share:
Basic: Weighted-average common stock	1,175		1,193		1,184		1,189
Add: weighted-average stock options and warrants	6		6		7		6
Diluted	1,181		1,199		1,191		1,195
Basic EPS:
Income from continuing operations attributable to common shareholders	$ 1.04		$ 0.91		$ 3.09	[1]	$ 2.49	[1]
Income from discontinued operations, net of tax					$ 0.03	[1]	$ 0	[1]
Net income attributable to common shareholders	$ 1.04	[2]	$ 0.91	[2]	$ 3.12	[1]	$ 2.49	[1]
Diluted EPS:
Income from continuing operations attributable to common shareholders	$ 1.03		$ 0.90		$ 3.08	[1]	$ 2.47	[1]
Income from discontinued operations, net of tax					$ (0.03)	[1]	$ 0	[1]
Net income attributable to common shareholders	$ 1.03	[2]	$ 0.90	[2]	$ 3.11	[1]	$ 2.47	[1]
Earnings Per Common Share (Textuals) [Abstract]
Subordinated debentures	$ 750		$ 750		$ 750		$ 750
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per Share, amount	19		36		19		37

[1] Represents income from continuing operations or net income, as applicable, less earnings allocated to participating share awards and other items of $44 million and $38 million for the nine months ended September 30, 2011 and 2010, respectively.

[2] Represents net income less earnings allocated to participating share awards and other items of $15 million and $13 million for the three months ended September 30, 2011 and 2010, respectively.