Earnings per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Earnings Per Share Basic and Diluted [Line Items]
Net income	$ 1,052	[1]	$ 1,115	[1]	$ 2,112	[1]	$ 2,110	[1]
Net income (loss) attributable to noncontrolling interests	3	[1]	4	[1]	1	[1]	(4)	[1]
Preferred stock dividends and discount accretion and redemptions	48		53		118		128
Net income attributable to common shareholders	1,001		1,058		1,993		1,986
Dividends and undistributed earnings allocated to nonvested restricted shares	3		5		6		9
Net income attributable to basic common shares	998		1,053		1,987		1,977
Less: Impact of BlackRock earnings per share dilution	3		4		9		9
Net income attributable to diluted common shares	$ 995		$ 1,049		$ 1,978		$ 1,968
Basic weighted-average common shares outstanding	532		528		532		527
Basic earnings per common share (b)	$ 1.88		$ 2.00		$ 3.73		$ 3.75
Dilutive potential common shares (c) (d)	7		3		7		3
Diluted weighted-average common shares outstanding	539		531		539		530
Diluted earnings per common share (b)	$ 1.85		$ 1.98		$ 3.67		$ 3.72
Stock Option [Member]
Earnings Per Share Basic and Diluted [Line Items]
Antidilutive securities excluded from computation of earnings per share amount	1		1		1		1
Warrant [Member]
Earnings Per Share Basic and Diluted [Line Items]
Antidilutive securities excluded from computation of earnings per share amount							17

[1] Amounts for 2013 periods have been updated to reflect the first quarter 2014 adoption of Accounting Standards Update (ASU) 2014-01 related to investments in low income housing tax credits.