Consolidated Condensed Statements Of Changes In Stockholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjusted Balance	Preferred Stock [Member]	Common Stock [Member]	Retained Earnings [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjustment	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjusted Balance	Treasury Stock At Cost [Member]	Accumulated Other Comprehensive Income (loss) [Member]
Balance at Dec. 31, 2019				$ 0	$ 459,389	$ 646,847			$ (127,633)	$ (9,589)
Net Income						22,372
Other comprehensive income (loss)										17,693
Dividends on common shares						(20,111)
Cash payment for fractional shares in dividend reinvestment plan					(1)
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures					3,865	528			2,500
Treasury Stock, Value, Acquired, Cost Method									7,507
Share-based Payment Arrangement, Expense					1,254
Common Stock, Dividends, Per Share, Cash Paid	$ 1.22
Stock Issued During Period, Shares, Restricted Stock Award, Gross	25,028
Stock issued during period, shares, withheld for tax, tax restricted stock	11,646
Treasury Stock, Shares, Acquired	76,000
Balance at Mar. 31, 2020				0	456,777	649,636			(132,640)	8,104
Balance at Dec. 31, 2019				0	$ 459,389	646,847			(127,633)	(9,589)
Net Income	$ 82,723
Other comprehensive income (loss)	23,789
Share-based Payment Arrangement, Expense	$ 3,700
Treasury Stock, Shares, Acquired					76,000
Balance at Sep. 30, 2020				0	$ 458,440	676,465			(132,109)	14,200
Balance at Mar. 31, 2020				0	456,777	649,636			(132,640)	8,104
Net Income						29,505
Other comprehensive income (loss)										5,757
Dividends on common shares						(16,837)
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures					142	7			96
Share-based Payment Arrangement, Expense					1,331
Common Stock, Dividends, Per Share, Cash Paid	$ 1.02
Stock Issued During Period, Shares, Restricted Stock Award, Gross	970
Stock issued during period, shares, withheld for tax, tax restricted stock	530
Balance at Jun. 30, 2020				0	457,966	662,311			(132,544)	13,861
Net Income	$ 30,846					30,846
Other comprehensive income (loss)	339									339
Dividends on common shares						(16,821)
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures					690	129			435
Share-based Payment Arrangement, Expense	$ 1,200				1,164
Common Stock, Dividends, Per Share, Cash Paid	$ 1.02
Stock Issued During Period, Shares, Restricted Stock Award, Gross	4,345
Stock issued during period, shares, withheld for tax, tax restricted stock	1,860
Balance at Sep. 30, 2020				0	458,440	676,465			(132,109)	14,200
Balance at Dec. 31, 2020	$ 1,040,256	$ (7,956)	$ 1,032,300	0	460,687	704,764			(130,766)	5,571
Balance (Accounting Standards Update 2016-13) at Dec. 31, 2020							$ (7,956)	$ 696,808
Net Income						42,831
Other comprehensive income (loss)										(13,472)
Dividends on common shares						(20,365)
Cash payment for fractional shares in dividend reinvestment plan					(1)
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures					3,988	44			2,174
Share-based Payment Arrangement, Expense					1,836
Common Stock, Dividends, Per Share, Cash Paid	$ 1.23
Stock Issued During Period, Shares, Restricted Stock Award, Gross	21,764
Stock issued during period, shares, withheld for tax, tax restricted stock	14,108
Balance at Mar. 31, 2021				0	458,534	719,230			(128,592)	(7,901)
Balance at Dec. 31, 2020	$ 1,040,256	$ (7,956)	$ 1,032,300	0	$ 460,687	704,764			(130,766)	5,571
Balance (Accounting Standards Update 2016-13) at Dec. 31, 2020							$ (7,956)	$ 696,808
Net Income	117,397
Other comprehensive income (loss)	(13,381)
Share-based Payment Arrangement, Expense	4,500
Treasury Stock, Shares, Acquired					137,659
Balance at Sep. 30, 2021	$ 1,067,912			0	$ 459,953	759,619			(143,850)	(7,810)
Balance at Mar. 31, 2021				0	458,534	719,230			(128,592)	(7,901)
Net Income						39,132
Other comprehensive income (loss)										4,971
Dividends on common shares						(17,081)
Cash payment for fractional shares in dividend reinvestment plan					(2)
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures					743	126			483
Share-based Payment Arrangement, Expense					1,487
Common Stock, Dividends, Per Share, Cash Paid	$ 1.03
Stock Issued During Period, Shares, Restricted Stock Award, Gross	4,834
Stock issued during period, shares, withheld for tax, tax restricted stock	2,973
Balance at Jun. 30, 2021				0	459,276	741,155			(128,109)	(2,930)
Net Income	$ 35,434					35,434
Other comprehensive income (loss)	(4,880)									(4,880)
Dividends on common shares						(16,999)
Cash payment for fractional shares in dividend reinvestment plan					(1)
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures					495	29			307
Treasury Stock, Value, Acquired, Cost Method									16,048
Share-based Payment Arrangement, Expense	$ 1,200				$ 1,173
Common Stock, Dividends, Per Share, Cash Paid	$ 1.03
Stock Issued During Period, Shares, Restricted Stock Award, Gross	3,079
Stock issued during period, shares, withheld for tax, tax restricted stock	1,348
Treasury Stock, Shares, Acquired	137,659				137,659
Balance at Sep. 30, 2021	$ 1,067,912			$ 0	$ 459,953	$ 759,619			$ (143,850)	$ (7,810)