CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Additional Paid In Capital Preferred Stock	Common Stock	Additional Paid In Capital Common Stock	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Total
BALANCE at Dec. 31, 2011	$ 83,027	$ 157	$ 1,443,883	$ 934,617	$ (116,001)	$ (33,940)	$ 2,311,743
Increase (Decrease) in Stockholders' Equity
Net income				281,650			281,650
Other comprehensive income (loss)						38,609	38,609
Stock compensation costs			12,668				12,668
Tax benefit from stock compensation plans, net			462				462
Issuance of 655,301, 323,737 and 336,031 shares of common stock pursuant to various stock compensation plans and agreements for the year ended December 31, 2014, 2013 and 2012 respectively			3,821				3,821
Issuance of 18,909, 19,998 and 26,151 shares pursuant to Director retainer fee for the year ended December 31, 2014, 2013 and 2012 respectively			570				570
Cancellation of 20,017, 65,686 and 190,634 shares of common stock due to forfeitures of issued restricted stock for the year ended December 31, 2014, 2013 and 2012 respectively			3,335		(3,335)
285,953, 508,518 and 137,258 shares of restricted stock surrendered due to employee tax liability for the year ended December 31, 2014, 2013 and 2012 respectively					(3,012)		(3,012)
Preferred stock dividends				(6,857)			(6,857)
Common stock dividends				(57,582)			(57,582)
Purchase of 8,026,807 and 9,068,105 shares of treasury stock pursuant to the Stock Repurchase Program for year ended December 31, 2013 and 2012 respectively					(199,950)		(199,950)
BALANCE at Dec. 31, 2012	83,027	157	1,464,739	1,151,828	(322,298)	4,669	2,382,122
Increase (Decrease) in Stockholders' Equity
Net income				295,045			295,045
Other comprehensive income (loss)						(35,128)	(35,128)
Stock compensation costs			13,548				13,548
Tax benefit from stock compensation plans, net			5,522				5,522
Issuance of 655,301, 323,737 and 336,031 shares of common stock pursuant to various stock compensation plans and agreements for the year ended December 31, 2014, 2013 and 2012 respectively			3,054				3,054
Issuance of 18,909, 19,998 and 26,151 shares pursuant to Director retainer fee for the year ended December 31, 2014, 2013 and 2012 respectively			630				630
Cancellation of 20,017, 65,686 and 190,634 shares of common stock due to forfeitures of issued restricted stock for the year ended December 31, 2014, 2013 and 2012 respectively			1,156		(1,156)
285,953, 508,518 and 137,258 shares of restricted stock surrendered due to employee tax liability for the year ended December 31, 2014, 2013 and 2012 respectively					(13,833)		(13,833)
Preferred stock dividends				(3,428)			(3,428)
Common stock dividends				(83,315)			(83,315)
Conversion of 85,710 shares of Series A preferred stock into 5,594,080 shares of common stock	(83,027)	6	83,021
Purchase of 8,026,807 and 9,068,105 shares of treasury stock pursuant to the Stock Repurchase Program for year ended December 31, 2013 and 2012 respectively					(199,992)		(199,992)
BALANCE at Dec. 31, 2013		163	1,571,670	1,360,130	(537,279)	(30,459)	2,364,225
Increase (Decrease) in Stockholders' Equity
Net income				342,483			342,483
Other comprehensive income (loss)						34,696	34,696
Stock compensation costs			13,883				13,883
Tax benefit from stock compensation plans, net			6,513				6,513
Issuance of 655,301, 323,737 and 336,031 shares of common stock pursuant to various stock compensation plans and agreements for the year ended December 31, 2014, 2013 and 2012 respectively		1	6,793				6,794
Issuance of 18,909, 19,998 and 26,151 shares pursuant to Director retainer fee for the year ended December 31, 2014, 2013 and 2012 respectively			630				630
Cancellation of 20,017, 65,686 and 190,634 shares of common stock due to forfeitures of issued restricted stock for the year ended December 31, 2014, 2013 and 2012 respectively			379		(379)
285,953, 508,518 and 137,258 shares of restricted stock surrendered due to employee tax liability for the year ended December 31, 2014, 2013 and 2012 respectively					(10,326)		(10,326)
Common stock dividends				(104,015)			(104,015)
Issuance of 5,583,093 shares pursuant to MetroCorp acquisition			73,044		117,786		190,830
Warrant acquired pursuant to MetroCorp acquisition			4,855				4,855
BALANCE at Dec. 31, 2014		$ 164	$ 1,677,767	$ 1,598,598	$ (430,198)	$ 4,237	$ 2,850,568