Consolidated Condensed Statements Of Changes In Stockholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Preferred Stock [Member]	Common Stock [Member]	Retained Earnings [Member]	Treasury Stock At Cost [Member]	Accumulated Other Comprehensive Income (loss) [Member]
Balance at Dec. 31, 2010		$ 97,290	$ 305,677	$ 406,342	$ (77,733)	$ (1,868)
Net Income	71,530			71,530
Other comprehensive income, net of tax:
Change in funded status of pension plan, net of income taxes
Unrealized net holding gain on cash flow hedge, net of income taxes	348					348
Unrealized net holding gain on securities available-for-sale, net of income taxes	644					644
Cash dividends on common stock at $2.82 per share				(43,425)
Cash payment for fractional shares in dividend reinvestment plan			(2)
Common stock warrant repurchased	0
Common stock warrants cancelled			(66)	66
Accretion of discount on preferred stock		642		(642)
Preferred stock dividends				(3,750)
Balance at Sep. 30, 2011		97,932	305,609	430,121	(77,733)	(876)
Balance at Dec. 31, 2011	742,364	98,146	305,499	424,557	(77,007)	(8,831)
Net Income	62,343			62,343
Other comprehensive income, net of tax:
Change in funded status of pension plan, net of income taxes	412					412
Unrealized net holding gain on cash flow hedge, net of income taxes	401					401
Unrealized net holding gain on securities available-for-sale, net of income taxes	1,468					1,468
Cash dividends on common stock at $2.82 per share				(43,445)
Cash payment for fractional shares in dividend reinvestment plan			(2)
Common stock warrant repurchased	(2,843)		(2,843)
Preferred stock repurchased		(100,000)
Accretion of discount on preferred stock		1,854		(1,854)
Preferred stock dividends				(1,571)
Balance at Sep. 30, 2012	$ 659,127	$ 0	$ 302,654	$ 440,030	$ (77,007)	$ (6,550)