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, 2011		$ 98,146	$ 305,499	$ 424,557	$ (77,007)	$ (8,831)
Net Income	31,475			31,475
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	113					113
Unrealized net holding loss on securities available-for-sale, net of income taxes	(2,202)					(2,202)
Cash dividends on common stock at $0.94 per share				(14,481)
Cash payment for fractional shares in dividend reinvestment plan			(1)
Accretion of discount on preferred stock		226		(227)
Preferred stock dividends				(1,250)
Balance at Mar. 31, 2012		98,372	305,498	440,074	(77,007)	(10,508)
Balance at Dec. 31, 2012	650,366	0	302,654	441,605	(76,375)	(17,518)
Net Income	20,710			20,710
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
Unrealized net holding loss on securities available-for-sale, net of income taxes	(2,379)					(2,379)
Cash dividends on common stock at $0.94 per share				(14,486)
Cash payment for fractional shares in dividend reinvestment plan			(1)
Balance at Mar. 31, 2013	$ 654,210	$ 0	$ 302,653	$ 447,829	$ (76,375)	$ (19,897)