Consolidated Statements Of Changes In Shareholders' Equity (USD $) In Millions, except Share data	Total		Nonredeemable Preferred Stock	Common Stock	Capital Surplus	Accumulated Other Comprehensive Loss	Retained Earnings	Treasury Stock
BALANCE at Dec. 31, 2009			$ 2,151	$ 894
BALANCE (in shares) at Dec. 31, 2009				151,200,000
Issuance of common stock				880
Redemption of preferred stock			(2,250)
Redemption discount accretion on preferred stock			(94)
BALANCE at Mar. 31, 2010
BALANCE at Dec. 31, 2009	7,029		2,151	894	740	(336)	5,161	(1,581)
BALANCE (in shares) at Dec. 31, 2009				151,200,000
Net income	277						277
Other comprehensive income (loss), net of tax	(53)					(53)
Cash dividends declared on preferred stock	(38)						(38)
Cash dividends declared on common stock	(44)						(44)
Purchase of common stock	(4)							(4)
Purchase of common stock (in shares)				(100,000)
Issuance of common stock	849			125	724
Issuance of common stock (in shares)				25,100,000
Redemption of preferred stock	(2,250)		(2,250)
Redemption discount accretion on preferred stock	0		94				(94)
Accretion of discount on preferred stock	0		5				(5)
Net issuance of common stock under employee stock plans	(2)				(11)		(10)	19
Net issuance of common stock under employee stock plans (in shares)				300,000
Share-based compensation	32				32
Other	(3)				(4)			1
BALANCE at Dec. 31, 2010	5,793		0	1,019	1,481	(389)	5,247	(1,565)
BALANCE (in shares) at Dec. 31, 2010				176,500,000
Net income	393						393
Other comprehensive income (loss), net of tax	33					33
Cash dividends declared on common stock	(75)						(75)
Purchase of common stock	(116)							(116)
Purchase of common stock (in shares)				(4,300,000)
Acquisition of Sterling Bancshares, Inc.	803			122	681
Acquisition of Sterling Bancshares, Inc. (in shares)				24,300,000
Net issuance of common stock under employee stock plans	0				(29)		(19)	48
Net issuance of common stock under employee stock plans (in shares)				800,000
Share-based compensation	37				37
BALANCE at Dec. 31, 2011	6,868		0	1,141	2,170	(356)	5,546	(1,633)
BALANCE (in shares) at Dec. 31, 2011				197,300,000
Net income	521						521
Other comprehensive income (loss), net of tax	(57)					(57)
Cash dividends declared on common stock	(106)						(106)
Purchase of common stock	(308)							(308)
Purchase of common stock (in shares)	(10,216,000)	[1]		(10,200,000)
Net issuance of common stock under employee stock plans	(13)				(46)		(30)	63
Net issuance of common stock under employee stock plans (in shares)				1,200,000
Share-based compensation	37				37
Other	0				1			(1)
BALANCE at Dec. 31, 2012	$ 6,942		$ 0	$ 1,141	$ 2,162	$ (413)	$ 5,931	$ (1,879)
BALANCE (in shares) at Dec. 31, 2012				188,300,000

[1] Includes approximately 162,000 shares shares purchased pursuant to deferred compensation plans and shares purchased from employees to pay for taxes related to restricted stock vesting under the terms of an employee share-based compensation plan during the year ended December 31, 2012 . These transactions are not considered part of the Corporation's repurchase program.