Consolidated Statements of Changes in Shareholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Preferred Stock	Common Stock	Warrant	Capital Surplus	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Treasury Stock
Beginning Balance at Dec. 31, 2012	$ 1,645,202	$ 0	$ 127,937	$ 0	$ 475,979	$ (16,205)	$ 1,195,850	$ (138,359)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	126,510						126,510
Other Comprehensive Income (Loss), Net of Tax	(67,408)					(67,408)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	59,102					(67,408)	126,510
Dividends, Preferred Stock, Cash	(3,868)						(3,868)
Cash dividends - common stock	(69,938)						(69,938)
Stock Issued During Period, Value, Acquisitions	925,272				925,272
Nonvested (restricted) shares granted	(6,814)				(19,257)			12,443
Restricted Stock Activity	(2,608)				956			(3,564)
Deferred compensation trust	0				391			(391)
Share-based compensation	8,747				8,747
Issuance of preferred stock	96,550	100,000			(3,450)
Adjustments to Additional Paid in Capital, Warrant Issued	3,000			3,000
Ending Balance at Sep. 30, 2013	2,654,645	100,000	127,937	3,000	1,388,638	(83,613)	1,248,554	(129,871)
Beginning Balance at Dec. 31, 2013	2,702,894	100,000	127,937	3,000	1,390,643	(66,876)	1,277,975	(129,785)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	176,872	0	0	0	0	0	176,872	0
Other Comprehensive Income (Loss), Net of Tax	17,293					17,293
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	194,165	0	0	0	0	17,293	176,872	0
Dividends, Preferred Stock, Cash	(4,407)	0	0	0	0	0	(4,407)	0
Cash dividends - common stock	(78,987)			0		0	(78,987)	0
Nonvested (restricted) shares granted	99			0	(13,029)	0	0	13,128
Restricted Stock Activity	(4,290)			0	952	0	0	(5,242)
Deferred compensation trust	0			0	684	0	0	(684)
Share-based compensation	10,957			0	10,957	0	0	0
Adjustments to Additional Paid in Capital, Warrant Issued	0
Ending Balance at Sep. 30, 2014	$ 2,820,431	$ 100,000	$ 127,937	$ 3,000	$ 1,390,207	$ (49,583)	$ 1,371,453	$ (122,583)