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, 2012		$ 0	$ 302,654,000	$ 441,605,000	$ (76,375,000)	$ (17,518,000)
Net Income	40,744,000			40,744,000
Other comprehensive income, net of tax:
Unrealized net holding gain (loss) on securities available-for-sale, net of income taxes	(22,916,000)					(22,916,000)
Cash dividends on common stock at $1.88 per share				(28,974,000)
Cash payment for fractional shares in dividend reinvestment plan			(1,000)
Allocated Share-based Compensation Expense	0
Balance at Jun. 30, 2013		0	302,653,000	453,375,000	(76,375,000)	(40,434,000)
Balance at Dec. 31, 2013	651,747,000	0	302,651,000	460,643,000	(76,128,000)	(35,419,000)
Net Income	41,446,000			41,446,000
Other comprehensive income, net of tax:
Unrealized net holding gain (loss) on securities available-for-sale, net of income taxes	24,020,000					24,020,000
Cash dividends on common stock at $1.88 per share				(28,975,000)
Cash payment for fractional shares in dividend reinvestment plan			(2,000)
Allocated Share-based Compensation Expense	220,000		220,000
Treasury Stock, Value, Acquired, Cost Method					(1,485,000)
Balance at Jun. 30, 2014	$ 686,971,000	$ 0	$ 302,869,000	$ 473,114,000	$ (77,613,000)	$ (11,399,000)