Consolidated Condensed Statements Of Changes In Stockholders' Equity - USD ($)	Total	Preferred Stock [Member]	Common Stock [Member]	Retained Earnings [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjustment	Treasury Stock At Cost [Member]	Accumulated Other Comprehensive Income (loss) [Member]
Balance at Dec. 31, 2018		$ 0	$ 358,598,000	$ 614,069,000		$ (90,373,000)	$ (49,788,000)
Balance (Accounting Standards Update 2016-02 [Member]) at Dec. 31, 2018				613,926,000	$ (143,000)
Net Income				25,455,000
Other comprehensive income (loss)							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)
Treasury Stock, Value, Acquired, Cost Method						8,502,000
Share-based Payment Arrangement, Expense			1,358,000
Balance at Mar. 31, 2019		0	357,475,000	619,971,000		(96,949,000)	(35,453,000)
Balance at Dec. 31, 2018		0	358,598,000	614,069,000		(90,373,000)	(49,788,000)
Balance (Accounting Standards Update 2016-02 [Member]) at Dec. 31, 2018				613,926,000	$ (143,000)
Net Income	$ 47,618,000
Other comprehensive income (loss)	23,481,000
Share-based Payment Arrangement, Expense	2,500,000
Balance at Jun. 30, 2019		0	456,911,000	625,227,000		(121,399,000)	(26,307,000)
Balance at Mar. 31, 2019		0	357,475,000	619,971,000		(96,949,000)	(35,453,000)
Net Income	22,163,000			22,163,000
Other comprehensive income (loss)	9,146,000						9,146,000
Dividends on common shares				(16,907,000)
Cash payment for fractional shares in dividend reinvestment plan			(1,000)
Treasury Stock, Value, Acquired, Cost Method						24,450,000
Share-based Payment Arrangement, Expense	1,200,000		1,162,000
Balance at Jun. 30, 2019		0	456,911,000	625,227,000		(121,399,000)	(26,307,000)
Proceeds from Issuance of Common Stock			98,275,000
Balance at Dec. 31, 2019	969,014,000	0	459,389,000	646,847,000		(127,633,000)	(9,589,000)
Net Income				22,372,000
Other comprehensive income (loss)							17,693,000
Dividends on common shares				(20,111,000)
Cash payment for fractional shares in dividend reinvestment plan			(1,000)
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures			(3,865,000)	(528,000)		(2,500,000)
Treasury Stock, Value, Acquired, Cost Method						7,507,000
Share-based Payment Arrangement, Expense			1,254,000
Balance at Mar. 31, 2020		0	456,777,000	649,636,000		(132,640,000)	8,104,000
Balance at Dec. 31, 2019	969,014,000	0	459,389,000	646,847,000		(127,633,000)	(9,589,000)
Net Income	51,877,000
Other comprehensive income (loss)	23,450,000
Share-based Payment Arrangement, Expense	2,600,000
Balance at Jun. 30, 2020	1,001,594,000	0	457,966,000	662,311,000		(132,544,000)	13,861,000
Balance at Mar. 31, 2020		0	456,777,000	649,636,000		(132,640,000)	8,104,000
Net Income	29,505,000			29,505,000
Other comprehensive income (loss)	5,757,000						5,757,000
Dividends on common shares				(16,837,000)
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures			(142,000)	(7,000)		(96,000)
Share-based Payment Arrangement, Expense	1,300,000		1,331,000
Balance at Jun. 30, 2020	$ 1,001,594,000	$ 0	$ 457,966,000	$ 662,311,000		$ (132,544,000)	$ 13,861,000