CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Total	Additional Paid In Capital Preferred Stock	Common Stock	Additional Paid In Capital Common Stock	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss), Net of Tax
BALANCE at Dec. 31, 2012	$ 2,382,122	$ 83,027	$ 157	$ 1,464,739	$ 1,151,828	$ (322,298)	$ 4,669
Increase (Decrease) in Stockholders' Equity
Net income	219,263				219,263
Other comprehensive income (loss)	(29,847)						(29,847)
Stock compensation costs	9,263			9,263
Tax benefit from stock compensation plans, net	3,301			3,301
Issuance of 398,012 and 285,921 shares of common stock pursuant to various stock compensation plans and agreements for the period ended September 30, 2014 and 2013, respectively	2,112			2,112
Issuance of 18,909 and 19,998 shares pursuant to Director retainer fee for the period ended September 30, 2014 and 2013, respectively	630			630
Cancellation of 17,337 and 58,929 shares of common stock due to forfeitures of issued restricted stock for the period ended September 30, 2014 and 2013, respectively				1,039		(1,039)
208,440 and 368,932 shares of restricted stock surrendered due to employee tax liability for the period ended September 30, 2014 and 2013, respectively	(9,049)					(9,049)
Preferred stock dividends	(3,428)				(3,428)
Common stock dividends	(62,499)				(62,499)
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 shares of treasury stock pursuant to the Stock Repurchase Program	(199,992)					(199,992)
BALANCE at Sep. 30, 2013	2,311,876		163	1,564,105	1,305,164	(532,378)	(25,178)
BALANCE at Dec. 31, 2013	2,364,225		163	1,571,670	1,360,130	(537,279)	(30,459)
Increase (Decrease) in Stockholders' Equity
Net income	249,485				249,485
Other comprehensive income (loss)	28,031						28,031
Stock compensation costs	10,382			10,382
Tax benefit from stock compensation plans, net	3,916			3,916
Issuance of 398,012 and 285,921 shares of common stock pursuant to various stock compensation plans and agreements for the period ended September 30, 2014 and 2013, respectively	1,249			1,249
Issuance of 18,909 and 19,998 shares pursuant to Director retainer fee for the period ended September 30, 2014 and 2013, respectively	630			630
Cancellation of 17,337 and 58,929 shares of common stock due to forfeitures of issued restricted stock for the period ended September 30, 2014 and 2013, respectively				323		(323)
208,440 and 368,932 shares of restricted stock surrendered due to employee tax liability for the period ended September 30, 2014 and 2013, respectively	(7,532)					(7,532)
Common stock dividends	(77,978)				(77,978)
Issuance of 5,583,093 shares pursuant to MetroCorp acquisition	190,830			73,044		117,786
Warrant acquired pursuant to MetroCorp acquisition	4,855			4,855
BALANCE at Sep. 30, 2014	$ 2,768,093		$ 163	$ 1,666,069	$ 1,531,637	$ (427,348)	$ (2,428)