Consolidated Statements of Changes in Shareholders' Equity - USD ($)	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, 2020	$ 692,472,000	$ 157,784,000	$ 296,186,000	$ 306,899,000	$ (22,144,000)	$ (46,253,000)
Beginning balance, shares at Dec. 31, 2020		29,295,052
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	91,801,000			91,801,000
Other comprehensive income (loss), net of income tax (benefit)	5,791,000				5,791,000
Cash dividends declared	(23,519,000)			(23,519,000)
Stock-based compensation	3,457,000		3,513,000	(56,000)
Stock issued under dividend reinvestment and employee stock purchase plans	2,384,000		153,000	(1,000)		2,232,000
Stock issued under dividend reinvestment and employee stock purchase plans, shares		86,187
Vesting of restricted stock unit awards	(355,000)		(1,153,000)			798,000
Vesting of restricted stock unit awards, shares		43,963
Exercise of stock options	2,058,000		155,000			1,903,000
Exercise of stock options, shares		93,033
Cancellations of performance-based restricted stock awards			327,000			(327,000)
Cancellations of performance-based restricted stock awards, shares		(7,199)
Purchases of treasury stock	(295,000)					(295,000)
Purchases of treasury stock, shares		(10,494)
Ending balance at Dec. 31, 2021	$ 773,794,000	$ 157,784,000	299,181,000	375,124,000	(16,353,000)	(41,942,000)
Ending balance, shares at Dec. 31, 2021		29,500,542
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared, per share	$ 0.80
Net income	$ 78,120,000			78,120,000
Other comprehensive income (loss), net of income tax (benefit)	(45,751,000)				(45,751,000)
Cash dividends declared	(24,399,000)			(24,399,000)
Stock-based compensation	3,781,000		3,989,000	(208,000)
Stock issued under dividend reinvestment and employee stock purchase plans	2,541,000		169,000			2,372,000
Stock issued under dividend reinvestment and employee stock purchase plans, shares		96,366
Vesting of restricted stock unit awards	(903,000)		(2,551,000)			1,648,000
Vesting of restricted stock unit awards, shares		92,073
Exercise of stock options	698,000		20,000			678,000
Exercise of stock options, shares		32,934
Purchases of treasury stock	(11,381,000)					(11,381,000)
Purchases of treasury stock, shares		(450,000)
Ending balance at Dec. 31, 2022	$ 776,500,000	$ 157,784,000	300,808,000	428,637,000	(62,104,000)	(48,625,000)
Ending balance, shares at Dec. 31, 2022		29,271,915
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared, per share	$ 0.83
Net income	$ 71,104,000			71,104,000
Other comprehensive income (loss), net of income tax (benefit)	11,458,000				11,458,000
Cash dividends declared	(24,717,000)			(24,717,000)
Stock-based compensation	3,877,000		4,210,000	(333,000)
Stock issued under dividend reinvestment and employee stock purchase plans	2,565,000		(78,000)			2,643,000
Stock issued under dividend reinvestment and employee stock purchase plans, shares		128,480
Vesting of restricted stock unit awards	(1,232,000)		(3,857,000)			2,625,000
Vesting of restricted stock unit awards, shares		131,601
Exercise of stock options	$ 115,000		(17,000)			132,000
Exercise of stock options, shares	6,210	6,210
Purchases of treasury stock	$ (462,000)					(462,000)
Purchases of treasury stock, shares		(26,485)
Ending balance at Dec. 31, 2023	$ 839,208,000	$ 157,784,000	$ 301,066,000	$ 474,691,000	$ (50,646,000)	$ (43,687,000)
Ending balance, shares at Dec. 31, 2023		29,511,721
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared, per share	$ 0.84