Consolidated Condensed Statements Of Changes In Stockholders' Equity - USD ($) $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Retained Earnings [Member]	Treasury Stock At Cost [Member]	Accumulated Other Comprehensive Income (loss) [Member]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	$ (1,924)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance		$ 0	$ 302,651	$ 458,719	$ (76,128)	$ (35,419)
Balance at Dec. 31, 2013		0	302,651	460,643	(76,128)	(35,419)
Net Income	41,387			41,387
Other comprehensive income, net of tax:
Unrealized net holding (loss) gain on securities available-for-sale, net of income taxes	24,020					24,020
Cash dividends on common shares at $1.88 per share				(28,975)
Cash payment for fractional shares in dividend reinvestment plan			(2)
Allocated Share-based Compensation Expense	220		220
Treasury Stock, Value, Acquired, Cost Method					(1,485)
Balance at Jun. 30, 2014		0	302,869	471,131	(77,613)	(11,399)
Balance at Dec. 31, 2013		0	302,651	460,643	(76,128)	(35,419)
Balance at Dec. 31, 2014	696,541	0	303,104	486,541	(77,439)	(13,608)
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	(2,057)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance		0	303,104	484,484	(77,439)	(13,608)
Net Income	40,083			40,083
Other comprehensive income, net of tax:
Unrealized net holding (loss) gain on securities available-for-sale, net of income taxes	(372)					(372)
Cash dividends on common shares at $1.88 per share				(28,975)
Cash payment for fractional shares in dividend reinvestment plan			(1)
Allocated Share-based Compensation Expense	470		470
Treasury Stock, Value, Acquired, Cost Method					(1,783)
Balance at Jun. 30, 2015	$ 705,963	$ 0	$ 303,573	$ 495,592	$ (79,222)	$ (13,980)