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, 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						176,872
Total other comprehensive gains/(losses), Net of Tax	17,293					17,293
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	194,165					17,293	176,872
Dividends, Preferred Stock, Cash	(4,407)						(4,407)
Cash dividends - common stock	(78,987)						(78,987)
Nonvested (restricted) shares granted	99				(13,029)			13,128
Restricted Stock Activity	(4,290)				952			(5,242)
Deferred compensation trust	0				684			(684)
Share-based compensation	10,957				10,957
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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Payments for Repurchase of Warrants	0
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	172,735	0	0	0	0	0	172,735	0
Total other comprehensive gains/(losses), Net of Tax	21,126					21,126
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	193,861					21,126	172,735
Dividends, Preferred Stock, Cash	(4,407)						(4,407)
Cash dividends - common stock	(80,800)						(80,800)
Nonvested (restricted) shares granted	0				(14,505)			14,505
Restricted Stock Activity	(4,300)				1,694			(5,994)
Deferred compensation trust	0				770			(770)
Share-based compensation	10,815				10,815
Ending Balance at Sep. 30, 2015	2,937,300	$ 100,000	$ 127,937	0	1,382,714	$ (50,766)	$ 1,492,245	$ (114,830)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustments to Additional Paid in Capital, Warrant Issued				$ (3,000)
Adjustments to Additional Paid in Capital, Warrant Issued					$ (9,150)
Payments for Repurchase of Warrants	$ (12,150)