Consolidated Condensed Statements Of Changes In Stockholders' Equity (USD $)	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		$ 97,290,000	$ 305,677,000	$ 406,342,000	$ (77,733,000)	$ (1,868,000)
Net Income	51,149,000			51,149,000
Other comprehensive loss, net of tax:
Change in funded status of pension plan, net of income taxes of $222
Unrealized net holding gain (loss) on cash flow hedge, net of income taxes	193,000					193,000
Unrealized net holding gain (loss) on securities available-for-sale, net of income tax benefit	(8,500,000)					(8,500,000)
Cash dividends on common stock at $1.88 per share				(28,951,000)
Cash payment for fractional shares in dividend reinvestment plan			(1,000)
Common stock warrant repurchased	0
Common stock warrants cancelled			(67,000)	67,000
Accretion of discount on preferred stock		428,000		(428,000)
Preferred stock dividends				(2,500,000)
Balance at Jun. 30, 2011		97,718,000	305,609,000	425,679,000	(77,733,000)	(10,175,000)
Balance at Dec. 31, 2011	742,364,000	98,146,000	305,499,000	424,557,000	(77,007,000)	(8,831,000)
Net Income	50,361,000			50,361,000
Other comprehensive loss, net of tax:
Change in funded status of pension plan, net of income taxes of $222	412,000					412,000
Unrealized net holding gain (loss) on cash flow hedge, net of income taxes	259,000					259,000
Unrealized net holding gain (loss) on securities available-for-sale, net of income tax benefit	604,000					604,000
Cash dividends on common stock at $1.88 per share				(28,962,000)
Cash payment for fractional shares in dividend reinvestment plan			(1,000)
Common stock warrant repurchased	2,843,000		2,843,000
Preferred stock repurchased		(100,000,000)
Accretion of discount on preferred stock		1,854,000		(1,854,000)
Preferred stock dividends				(1,571,000)
Balance at Jun. 30, 2012	$ 660,623,000	$ 0	$ 302,655,000	$ 442,531,000	$ (77,007,000)	$ (7,556,000)