Consolidated Statements Of Changes In Shareholders' Equity (USD $)	Preferred Stock [Member]	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]	Total
BALANCE, VALUE at Dec. 31, 2009	$ 204,335,000	$ 1,253,288,000	$ 83,939,000	$ 24,955,000	$ 1,566,517,000
BALANCE, SHARES at Dec. 31, 2009		86,785,588
Net income			28,326,000		28,326,000
Other comprehensive loss, net of tax				(10,000)	(10,000)
Comprehensive income					28,316,000
Issuance of common stock, shares		8,625,000
Issuance of common stock, value		89,786,000			89,786,000
Stock-based compensation		3,505,000			3,505,000
Stock repurchased and retired, shares		(22,541)
Stock repurchased and retired, value		(284,000)			(284,000)
Issuances of common stock under stock plans and related net tax benefit, shares		173,767
Issuances of common stock under stock plans and related net tax benefit, value		844,000			844,000
Redemption of preferred stock issued to U.S. Treasury	(214,181,000)				(214,181,000)
Issuance of preferred stock	198,289,000				198,289,000
Conversion of preferred stock to common stock, shares		18,975,000
Conversion of preferred stock to common stock, value	(198,289,000)	198,289,000
Amortization of discount on preferred stock	9,846,000		(9,846,000)
Dividends declared on preferred stock			(3,686,000)		(3,686,000)
Repurchase of warrants issued to U.S. Treasury		(4,500,000)			(4,500,000)
Cash dividends on common stock			(22,032,000)		(22,032,000)
BALANCE, VALUE at Dec. 31, 2010		1,540,928,000	76,701,000	24,945,000	1,642,574,000
BALANCE, SHARES at Dec. 31, 2010		114,536,814
Net income			74,496,000		74,496,000
Other comprehensive loss, net of tax				8,829,000	8,829,000
Comprehensive income					83,325,000
Stock-based compensation		3,785,000			3,785,000
Stock repurchased and retired, shares		(2,557,056)
Stock repurchased and retired, value		(29,754,000)			(29,754,000)
Issuances of common stock under stock plans and related net tax benefit, shares		185,133
Issuances of common stock under stock plans and related net tax benefit, value		(46,000)			(46,000)
Cash dividends on common stock			(27,471,000)		(27,471,000)
BALANCE, VALUE at Dec. 31, 2011		1,514,913,000	123,726,000	33,774,000	1,672,413,000
BALANCE, SHARES at Dec. 31, 2011		112,164,891			112,164,891
Net income			101,891,000		101,891,000
Other comprehensive loss, net of tax				(9,428,000)	(9,428,000)
Comprehensive income					92,463,000
Stock-based compensation		4,041,000			4,041,000
Stock repurchased and retired, shares		(596,000)
Stock repurchased and retired, value		(7,436,000)			(7,436,000)
Issuances of common stock under stock plans and related net tax benefit, shares		321,068
Issuances of common stock under stock plans and related net tax benefit, value		882,000			882,000
Cash dividends on common stock			(38,324,000)		(38,324,000)
BALANCE, VALUE at Dec. 31, 2012		$ 1,512,400,000	$ 187,293,000	$ 24,346,000	$ 1,724,039,000
BALANCE, SHARES at Dec. 31, 2012		111,889,959			111,889,959