Consolidated Condensed Statements Of Changes In Stockholders' Equity (USD $) In Thousands	Preferred Stock [Member]	Common Stock [Member]	Retained Earnings [Member]	Treasury Stock At Cost [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Comprehensive Income (loss) [Member]	Total
Balance at Dec. 31, 2009	$ 96,483	$ 306,569	$ 423,872	$ (125,321)	$ 15,661
Net Income			41,945			41,945	41,945
Other comprehensive income (loss), net of tax:
Unrealized net holding gain (loss) on cash flow hedge, net of income taxes					(211)	(211)
Unrealized net holding gain (loss) on securities available-for-sale, net of income taxes					429	429
Total comprehensive income						42,163
Cash dividends on common stock at $1.88 per share			(28,285)
Cash payment for fractional shares in dividend reinvestment plan		(2)					(2)
Reissuance of common stock from treasury shares held for warrants issued		(600)	(7,393)	29,292
Accretion of discount on preferred stock	403		(403)
Preferred stock dividends			(2,500)
Balance at Jun. 30, 2010	96,886	305,967	427,236	(96,029)	15,879
Balance at Dec. 31, 2010	97,290	305,677	422,458	(77,733)	(1,868)		745,824
Net Income			41,695			41,695	41,695
Other comprehensive income (loss), net of tax:
Unrealized net holding gain (loss) on cash flow hedge, net of income taxes					193	193
Unrealized net holding gain (loss) on securities available-for-sale, net of income taxes					(8,500)	(8,500)
Total comprehensive income						33,388
Cash dividends on common stock at $1.88 per share			(28,951)
Cash payment for fractional shares in dividend reinvestment plan		(1)					(1)
Common stock warrants cancelled		(67)	67
Accretion of discount on preferred stock	428		(428)
Preferred stock dividends			(2,500)
Balance at Jun. 30, 2011	$ 97,718	$ 305,609	$ 432,341	$ (77,733)	$ (10,175)		$ 747,760