Condensed Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Treasury Stock, Common
Beginning balance at Dec. 31, 2021	$ 773,794	$ 157,784	$ 299,181	$ 375,124	$ (16,353)	$ (41,942)
Beginning balance, shares at Dec. 31, 2021		29,500,542
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	33,483			33,483
Other comprehensive income, net of income tax	(26,428)				(26,428)
Cash dividends declared	(12,105)			(12,105)
Stock-based compensation	1,802		2,009	(207)		0
Stock issued under dividend reinvestment and employee stock purchase plans	1,275		104	0		1,171
Stock issued under dividend reinvestment and employee stock purchase plans, shares		47,617
Vesting of restricted stock units, net of shares withheld to cover taxes	(901)		(2,544)			1,643
Vesting of restricted stock unit awards, shares		91,835
Exercise of stock options	575		50			525
Shares under option, exercised		25,781
Purchases of treasury stock	(7,570)					(7,570)
Purchases of treasury stock, shares		(300,000)
Ending balance at Jun. 30, 2022	$ 763,925	$ 157,784	298,800	396,295	(42,781)	(46,173)
Ending balance, shares at Jun. 30, 2022		29,365,775
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared, per share	$ 0.41
Beginning balance at Mar. 31, 2022	$ 773,855	$ 157,784	297,945	389,332	(31,909)	(39,297)
Beginning balance, shares at Mar. 31, 2022		29,636,425
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	13,166			13,166
Other comprehensive income, net of income tax	(10,872)				(10,872)
Cash dividends declared	(6,200)			(6,200)
Stock-based compensation	933		936	(3)		0
Stock issued under dividend reinvestment and employee stock purchase plans	652		45			607
Stock issued under dividend reinvestment and employee stock purchase plans, shares		25,774
Vesting of restricted stock units, net of shares withheld to cover taxes	(38)		(126)			88
Vesting of restricted stock unit awards, shares		3,576
Exercise of stock options	(1)					(1)
Purchases of treasury stock	(7,570)					(7,570)
Purchases of treasury stock, shares		(300,000)
Ending balance at Jun. 30, 2022	$ 763,925	$ 157,784	298,800	396,295	(42,781)	(46,173)
Ending balance, shares at Jun. 30, 2022		29,365,775
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared, per share	$ 0.21
Beginning balance at Dec. 31, 2022	$ 776,500	$ 157,784	300,808	428,637	(62,104)	(48,625)
Beginning balance, shares at Dec. 31, 2022		29,271,915
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	37,834			37,834
Other comprehensive income, net of income tax	1,070				1,070
Cash dividends declared	(12,331)			(12,331)
Stock-based compensation	1,957		2,291	(334)
Stock issued under dividend reinvestment and employee stock purchase plans	1,309		(19)			1,328
Stock issued under dividend reinvestment and employee stock purchase plans, shares		61,636
Vesting of restricted stock units, net of shares withheld to cover taxes	(1,231)		(3,850)			2,619
Vesting of restricted stock unit awards, shares		131,363
Exercise of stock options	$ 114		(18)			132
Shares under option, exercised	6,210	6,210
Ending balance at Jun. 30, 2023	$ 805,222	$ 157,784	299,212	453,806	(61,034)	(44,546)
Ending balance, shares at Jun. 30, 2023		29,471,124
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared, per share	$ 0.42
Beginning balance at Mar. 31, 2023	$ 798,496	$ 157,784	298,167	443,493	(55,550)	(45,398)
Beginning balance, shares at Mar. 31, 2023		29,427,696
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	16,800			16,800
Other comprehensive income, net of income tax	(5,484)				(5,484)
Cash dividends declared	(6,180)			(6,180)
Stock-based compensation	927		1,234	(307)
Stock issued under dividend reinvestment and employee stock purchase plans	647		(48)			695
Stock issued under dividend reinvestment and employee stock purchase plans, shares		36,292
Vesting of restricted stock units, net of shares withheld to cover taxes	(24)		(137)			113
Vesting of restricted stock unit awards, shares		5,093
Exercise of stock options	40		(4)			44
Shares under option, exercised		2,043
Ending balance at Jun. 30, 2023	$ 805,222	$ 157,784	$ 299,212	$ 453,806	$ (61,034)	$ (44,546)
Ending balance, shares at Jun. 30, 2023		29,471,124
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared, per share	$ 0.21