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]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (loss) [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption | Adjustments for New Accounting Pronouncement [Member]							$ 3,806,000	$ (3,806,000)
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	$ 995,000					$ 3,806,000
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets | Accounting Standards Update 2016-01 [Member]				$ (1,917,000)		995,000
Balance at Dec. 31, 2017		$ 0	$ 307,726,000	561,908,000	$ (87,079,000)	(26,454,000)
Net Income	31,123,000			31,123,000
Other comprehensive income, net of tax:
Unrealized net holding (loss) gain on securities available-for-sale, net of income taxes	(23,410,000)					(21,386,000)
Dividends on common shares				(14,496,000)
Cash payment for fractional shares in dividend reinvestment plan			(1,000)
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures			(1,597,000)	(317,000)	(1,304,000)
Allocated Share-based Compensation Expense	1,100,000		1,121,000
Balance at Mar. 31, 2018		0	307,249,000	583,941,000	(85,775,000)	(52,641,000)
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets | Adjustments for Change in Accounting Principle [Domain]				(143,000)
Balance at Dec. 31, 2018	832,506,000	0	358,598,000	614,069,000	(90,373,000)	(49,788,000)
Net Income	25,455,000			25,455,000
Other comprehensive income, net of tax:
Unrealized net holding (loss) gain on securities available-for-sale, net of income taxes	14,541,000					14,335,000
Dividends on common shares				(19,137,000)
Cash payment for fractional shares in dividend reinvestment plan			(1,000)
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures			(2,480,000)	(273,000)	(1,926,000)
Allocated Share-based Compensation Expense	1,400,000		1,358,000
Treasury Stock, Value, Acquired, Cost Method					8,502,000
Balance at Mar. 31, 2019	$ 845,044,000	$ 0	$ 357,475,000	$ 619,971,000	$ (96,949,000)	$ (35,453,000)