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, 2012		$ 0	$ 302,654	$ 441,605	$ (76,375)	$ (17,518)
Net Income	59,773			59,773
Other comprehensive income, net of tax:
Unrealized net holding gain (loss) on securities available-for-sale, net of income taxes	(33,931)					(33,931)
Cash dividends on common stock at $2.82 per share				(43,461)
Cash payment for fractional shares in dividend reinvestment plan			(2)
Allocated Share-based Compensation Expense	0
Balance at Sep. 30, 2013		0	302,652	457,917	(76,375)	(51,449)
Balance at Dec. 31, 2013	651,747	0	302,651	460,643	(76,128)	(35,419)
Net Income	59,749			59,749
Other comprehensive income, net of tax:
Unrealized net holding gain (loss) on securities available-for-sale, net of income taxes	21,115					21,115
Cash dividends on common stock at $2.82 per share				(43,462)
Cash payment for fractional shares in dividend reinvestment plan			(3)
Allocated Share-based Compensation Expense	355		355
Treasury Stock, Value, Acquired, Cost Method					(1,485)
Balance at Sep. 30, 2014	$ 688,016	$ 0	$ 303,003	$ 476,930	$ (77,613)	$ (14,304)