Consolidated Statements of Shareholders' Equity and Comprehensive Income (USD $) In Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]	Treasury Stock [Member]
Beginning Balance at Dec. 31, 2009	$ 1,936,482	$ 370,290	$ 482,491	$ 1,257,730	$ 71,999	$ 7,458	$ (253,486)
Beginning Balance (in shares) at Dec. 31, 2009			176,364
Comprehensive income:
Net Income	96,842				96,842
Other comprehensive income	28,332					28,332
Total comprehensive income	125,174
Stock issued, including related tax benefits	230,239		55,751	171,205			3,283
Stock issued, including related tax benefits (in shares)			22,519
Stock-based compensation awards	1,428			1,428
Redemption Of Preferred Stock And Warrant	(387,300)	(376,500)		(10,800)
Preferred stock discount accretion	0	6,210			(6,210)
Preferred stock cash dividends	(12,498)				(12,498)
Common stock cash dividends	(17,215)				(17,215)
Balance at Sep. 30, 2010	1,876,310	0	538,242	1,419,563	132,918	35,790	(250,203)
Ending Balance (in shares) at Sep. 30, 2010			198,883
Beginning Balance at Dec. 31, 2010	1,880,389	0	538,492	1,420,127	158,453	12,495	(249,178)
Beginning Balance (in shares) at Dec. 31, 2010			199,050
Comprehensive income:
Net Income	109,494				109,494
Other comprehensive income	14,416					14,416
Total comprehensive income	123,910
Stock issued, including related tax benefits	4,848		1,508	(451)			3,791
Stock issued, including related tax benefits (in shares)			841
Stock-based compensation awards	3,473			3,473
Common stock cash dividends	(27,961)				(27,961)
Balance at Sep. 30, 2011	$ 1,984,659	$ 0	$ 540,000	$ 1,423,149	$ 239,986	$ 26,911	$ (245,387)
Ending Balance (in shares) at Sep. 30, 2011			199,891