Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Warrant	Capital Surplus	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Treasury Stock
Beginning Balance at Dec. 31, 2014	$ 2,834,281	$ 100,000	$ 127,937	$ 3,000	$ 1,393,090	$ (71,892)	$ 1,404,717	$ (122,571)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	57,139						57,139
Other comprehensive income	22,625					22,625
Comprehensive income	79,764					22,625	57,139
Dividends, Preferred Stock, Cash	(1,469)						(1,469)
Cash dividends - common stock	(26,461)						(26,461)
Nonvested (restricted) shares granted	0				(2,631)			2,631
Restricted Stock Activity	(970)				326			(1,296)
Deferred compensation trust	0				507			(507)
Share-based compensation	3,641				3,641
Ending Balance at Mar. 31, 2015	2,888,786	100,000	127,937	3,000	1,394,933	(49,267)	1,433,926	(121,743)
Beginning Balance at Dec. 31, 2015	2,940,095	100,000	127,937	0	1,386,677	(79,274)	1,519,438	(114,683)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	54,136					0	54,136
Other comprehensive income	30,933					30,933
Comprehensive income	85,069					30,933	54,136
Dividends, Preferred Stock, Cash	(1,469)					0	(1,469)
Cash dividends - common stock	(28,129)						(28,129)
Nonvested (restricted) shares granted	0				(364)			364
Restricted Stock Activity	(888)				272			(1,160)
Deferred compensation trust	0				652			(652)
Share-based compensation	3,279				3,279			0
Ending Balance at Mar. 31, 2016	$ 2,997,957	$ 100,000	$ 127,937	$ 0	$ 1,390,516	$ (48,341)	$ 1,543,976	$ (116,131)