Consolidated Statements of Changes in Stockholder's Equity (Unaudited) (USD $) In Thousands, unless otherwise specified	Total	Preferred Equity	Common Stock	Surplus	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning balance at Dec. 31, 2011	$ 2,865,794	$ 63,272	$ 1,746	$ 1,586,401	$ 1,148,773	$ 65,602	$ 0
Comprehensive (loss) income:
Net income	42,633	0	0	0	42,633	0	0
Other comprehensive income (loss)	(324)	0	0	0	0	(324)	0
Comprehensive income	42,309
Common stock issued:
Stock-based compensation plans, net	119	0	4	136	(124)	0	103
Purchase of treasury stock	(1,113)	0	0	0	0	0	(1,113)
Cash dividends:
Common stock	(8,735)	0	0	0	(8,735)	0	0
Preferred stock	(1,300)	0	0	0	(1,300)	0	0
Redemption of preferred stock	0	0	0	0	0	0	0
Issuance of preferred stock	0	0
Accretion of preferred stock discount	0	0	0	0	0	0	0
Stock-based compensation expense, net	3,794	0	0	3,794	0	0	0
Tax benefit of stock options	5	0	0	5	0	0	0
Ending balance at Mar. 31, 2012	2,900,873	63,272	1,750	1,590,336	1,181,247	65,278	(1,010)
Beginning balance at Dec. 31, 2012	2,936,399	63,272	1,750	1,602,136	1,281,811	48,603	(61,173)
Comprehensive (loss) income:
Net income	47,388	0	0	0	47,388	0	0
Other comprehensive income (loss)	(5,612)	0	0	0	0	(5,612)	0
Comprehensive income	41,776
Common stock issued:
Stock-based compensation plans, net	2,177	0	0	9	(16,724)	0	18,892
Purchase of treasury stock	(33,125)	0	0	0	0	0	(33,125)
Cash dividends:
Common stock	(13,483)	0	0	0	(13,483)	0	0
Preferred stock	(1,300)	0	0	0	(1,300)	0	0
Stock-based compensation expense, net	3,762	0	0	3,762	0	0	0
Tax benefit of stock options	59	0	0	59	0	0	0
Ending balance at Mar. 31, 2013	$ 2,936,265	$ 63,272	$ 1,750	$ 1,605,966	$ 1,297,692	$ 42,991	$ (75,406)