Consolidated Statements of Changes in Shareholders' Equity (USD $) In Thousands	Total	Preferred Stock	Common Stock	Capital Surplus	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Treasury Stock
Beginning Balance at Dec. 31, 2011	$ 1,565,953	$ 0	$ 127,937	$ 479,882	$ (23,887)	$ 1,131,203	$ (149,182)
Net income	30,344					30,344
Cash dividends - common stock	(17,337)					(17,337)
Nonvested (restricted) shares granted	0			(126)			126
Treasury Stock, Value, Acquired, Cost Method	(739)			574			(1,313)
Deferred compensation trust	0			(8)			8
Share-based compensation	4,169			4,169
Net unrealized gains on investment securities, net of taxes	1,715				1,715
Ending Balance at Mar. 31, 2012	1,584,105	0	127,937	484,491	(22,172)	1,144,210	(150,361)
Beginning Balance at Dec. 31, 2012	1,645,202	0	127,937	475,979	(16,205)	1,195,850	(138,359)
Net income	37,346					37,346
Dividends, Preferred Stock, Cash	(930)					(930)
Cash dividends - common stock	(17,377)					(17,377)
Nonvested (restricted) shares granted	0			(2,270)			2,270
Treasury Stock, Value, Acquired, Cost Method	(19)			606			(625)
Deferred compensation trust	0			118			(118)
Share-based compensation	1,972			1,972			0
Issuance of preferred stock	96,570	100,000		(3,430)
Net unrealized gains on investment securities, net of taxes	(7,914)				(7,914)
Ending Balance at Mar. 31, 2013	$ 1,754,850	$ 100,000	$ 127,937	$ 472,975	$ (24,119)	$ 1,214,889	$ (136,832)