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	146,106				146,106
Other comprehensive income (loss)	(26,347)						(26,347)
Stock compensation costs	5,898			5,898
Tax benefit from stock compensation plans, net	2,803			2,803
Issuance of 390,195 and 245,261 shares of common stock pursuant to various stock compensation plans and agreements for the period ended June 30, 2014 and 2013, respectively	1,150			1,150
Cancellation of 12,959 and 44,793 shares of common stock due to forfeitures of issued restricted stock for the period ended June 30, 2014 and 2013, respectively				804		(804)
202,070 and 356,426 shares of restricted stock surrendered due to employee tax liability for the period ended June 30, 2014 and 2013, respectively	(8,667)					(8,667)
Preferred stock dividends	(3,428)				(3,428)
Common stock dividends	(41,694)				(41,694)
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 Jun. 30, 2013	2,257,951		163	1,558,415	1,252,812	(531,761)	(21,678)
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	160,729				160,729
Other comprehensive income (loss)	27,924						27,924
Stock compensation costs	6,745			6,745
Tax benefit from stock compensation plans, net	3,787			3,787
Issuance of 390,195 and 245,261 shares of common stock pursuant to various stock compensation plans and agreements for the period ended June 30, 2014 and 2013, respectively	1,207			1,207
Cancellation of 12,959 and 44,793 shares of common stock due to forfeitures of issued restricted stock for the period ended June 30, 2014 and 2013, respectively				241		(241)
202,070 and 356,426 shares of restricted stock surrendered due to employee tax liability for the period ended June 30, 2014 and 2013, respectively	(7,308)					(7,308)
Common stock dividends	(51,970)				(51,970)
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 Jun. 30, 2014	$ 2,701,024		$ 163	$ 1,661,549	$ 1,468,889	$ (427,042)	$ (2,535)