CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Common Stock	Paid In Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)
Beginning balance, net of tax at Dec. 31, 2021	$ 912,172	$ 47,461	$ 780,501	$ 179,813	$ (155,308)	$ 59,705
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	24,996			24,996
Other comprehensive income (loss)	(139,976)					(139,976)
Issuance of common stock for dividend reinvestment plan	322	10	312
Purchase of common stock	(3,358)				(3,358)
Stock compensation expense	819		819
Net issuance of common stock under employee stock plans	269		182	(67)	154
Cash dividends paid on common stock	(11,003)			(11,003)
Ending balance, net of tax at Mar. 31, 2022	784,241	47,471	781,814	193,739	(158,512)	(80,271)
Beginning balance, net of tax at Dec. 31, 2021	912,172	47,461	780,501	179,813	(155,308)	59,705
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	50,401
Other comprehensive income (loss)	(199,040)
Ending balance, net of tax at Jun. 30, 2022	731,782	47,481	782,511	208,171	(167,046)	(139,335)
Beginning balance, net of tax at Mar. 31, 2022	784,241	47,471	781,814	193,739	(158,512)	(80,271)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	25,405			25,405
Other comprehensive income (loss)	(59,064)					(59,064)
Issuance of common stock for dividend reinvestment plan	313	10	303
Purchase of common stock	(8,842)				(8,842)
Stock compensation expense	847		847
Net issuance of common stock under employee stock plans	(212)		(453)	(67)	308
Cash dividends paid on common stock	(10,906)			(10,906)
Ending balance, net of tax at Jun. 30, 2022	731,782	47,481	782,511	208,171	(167,046)	(139,335)
Beginning balance, net of tax at Dec. 31, 2022	745,997	47,501	784,545	239,610	(188,203)	(137,456)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	26,034			26,034
Other comprehensive income (loss)	4,144					4,144
Issuance of common stock for dividend reinvestment plan	302	10	292
Purchase of common stock	(15,945)				(15,945)
Stock compensation expense	914		914
Net issuance of common stock under employee stock plans	572		368	(91)	295
Cash dividends paid on common stock	(10,988)			(10,988)
Ending balance, net of tax at Mar. 31, 2023	751,030	47,511	786,119	254,565	(203,853)	(133,312)
Beginning balance, net of tax at Dec. 31, 2022	745,997	47,501	784,545	239,610	(188,203)	(137,456)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	50,927
Other comprehensive income (loss)	21,763
Ending balance, net of tax at Jun. 30, 2023	765,161	47,524	787,027	268,643	(222,340)	(115,693)
Beginning balance, net of tax at Mar. 31, 2023	751,030	47,511	786,119	254,565	(203,853)	(133,312)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	24,893			24,893
Other comprehensive income (loss)	17,619					17,619
Issuance of common stock for dividend reinvestment plan	299	13	286
Purchase of common stock	(18,725)				(18,725)
Stock compensation expense	924		924
Net issuance of common stock under employee stock plans	(159)		(302)	(95)	238
Cash dividends paid on common stock	(10,720)			(10,720)
Ending balance, net of tax at Jun. 30, 2023	$ 765,161	$ 47,524	$ 787,027	$ 268,643	$ (222,340)	$ (115,693)