Consolidated Statements Of Changes In Shareholders' Equity (USD $) In Millions	Preferred Stock [Member]	Common Stock [Member]	Capital Surplus [Member]	Accumulated Other Comprehensive Loss [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Total
BALANCE at Dec. 31, 2009	$ 2,151	$ 894	$ 740	$ (336)	$ 5,161	$ (1,581)	$ 7,029
BALANCE (in shares) at Dec. 31, 2009		151.2
Net income					181		181
Other comprehensive income, net of tax				98			98
Total comprehensive income							279
Cash dividends declared on preferred stock					(38)		(38)
Cash dividends declared on common stock ($0.30 and $0.15 per share for the nine months ended 2011 and 2010, respectively)					(26)		(26)
Purchase of common stock						(4)	(4)
Purchase of common stock (in shares)		(0.1)
Issuance of common stock		125	724				849
Issuance of common stock (in shares)		25.1
Redemption of preferred stock	(2,250)						(2,250)
Redemption discount accretion on preferred stock	94				(94)
Accretion of discount on preferred stock	5				(5)
Net issuance of common stock under employee stock plans			(11)		(8)	16	(3)
Net issuance of common stock under employee stock plans (in shares)		0.3
Share-based compensation			24				24
Other			(4)			1	(3)
BALANCE at Sep. 30, 2010		1,019	1,473	(238)	5,171	(1,568)	5,857
BALANCE (in shares) at Sep. 30, 2010		176.5
BALANCE at Dec. 31, 2010		1,019	1,481	(389)	5,247	(1,565)	5,793
BALANCE (in shares) at Dec. 31, 2010		176.5
Net income					297		297
Other comprehensive income, net of tax				159			159
Total comprehensive income							456
Cash dividends declared on common stock ($0.30 and $0.15 per share for the nine months ended 2011 and 2010, respectively)					(55)		(55)
Purchase of common stock						(75)	(75)
Purchase of common stock (in shares)		(2.7)
Acquisition of Sterling Bancshares, Inc.		122	681				803
Acquisition of Sterling Bancshares, Inc. (in shares)		24.3
Net issuance of common stock under employee stock plans			(29)		(18)	47
Net issuance of common stock under employee stock plans (in shares)		0.8
Share-based compensation			29				29
BALANCE at Sep. 30, 2011		$ 1,141	$ 2,162	$ (230)	$ 5,471	$ (1,593)	$ 6,951
BALANCE (in shares) at Sep. 30, 2011		198.9