CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
Common stock, shares outstanding at Dec. 31, 2020		17,265,000
Shareholders' equity at Dec. 31, 2020	$ 534,195	$ 1,085	$ 125,610	$ 418,246	$ (7,391)	$ (3,355)
Net income	56,682			56,682
Total other comprehensive income (loss), net of tax	(10,737)				(10,737)
Cash dividends declared	(27,362)			(27,362)
Share-based compensation	2,705		2,705
Exercise of stock options and issuance of other compensation-related equity awards, net of awards surrendered, shares		55,000
Exercise of stock options and issuance of other compensation-related equity awards, net of awards surrendered, value	(165)	$ 0	(2,050)			1,885
Common stock, shares outstanding at Sep. 30, 2021		17,320,000
Shareholders' equity at Sep. 30, 2021	555,318	$ 1,085	126,265	447,566	(18,128)	(1,470)
Common stock, shares outstanding at Jun. 30, 2021		17,320,000
Shareholders' equity at Jun. 30, 2021	547,856	$ 1,085	125,442	437,927	(15,128)	(1,470)
Net income	18,751			18,751
Total other comprehensive income (loss), net of tax	(3,000)				(3,000)
Cash dividends declared	(9,112)			(9,112)
Share-based compensation	823		823
Common stock, shares outstanding at Sep. 30, 2021		17,320,000
Shareholders' equity at Sep. 30, 2021	$ 555,318	$ 1,085	126,265	447,566	(18,128)	(1,470)
Common stock, shares outstanding at Dec. 31, 2021	17,330,818	17,331,000
Shareholders' equity at Dec. 31, 2021	$ 564,808	$ 1,085	126,511	458,310	(19,981)	(1,117)
Net income	55,108			55,108
Total other comprehensive income (loss), net of tax	(151,774)				(151,774)
Cash dividends declared	(28,255)			(28,255)
Share-based compensation	2,589		2,589
Exercise of stock options and issuance of other compensation-related equity awards, net of awards surrendered, shares		34,000
Exercise of stock options and issuance of other compensation-related equity awards, net of awards surrendered, value	$ (723)	$ 0	(2,045)			1,322
Treasury stock purchased under Stock Repurchase Program, shares acquired	(194,000)
Treasury stock purchased under Stock Repurchase Program, amount acquired	$ (9,479)					(9,479)
Common stock, shares outstanding at Sep. 30, 2022	17,171,147	17,171,000
Shareholders' equity at Sep. 30, 2022	$ 432,274	$ 1,085	127,055	485,163	(171,755)	(9,274)
Common stock, shares outstanding at Jun. 30, 2022		17,190,000
Shareholders' equity at Jun. 30, 2022	476,634	$ 1,085	126,079	475,889	(118,041)	(8,378)
Net income	18,668			18,668
Total other comprehensive income (loss), net of tax	(53,714)				(53,714)
Cash dividends declared	(9,394)			(9,394)
Share-based compensation	$ 976		976
Treasury stock purchased under Stock Repurchase Program, shares acquired	(19,000)
Treasury stock purchased under Stock Repurchase Program, amount acquired	$ (896)					(896)
Common stock, shares outstanding at Sep. 30, 2022	17,171,147	17,171,000
Shareholders' equity at Sep. 30, 2022	$ 432,274	$ 1,085	$ 127,055	$ 485,163	$ (171,755)	$ (9,274)