CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock Shares Outstanding	Common Stock Amount Issued	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss)/Income	Treasury Stock	Deferred Compensation Arrangements	Total
Balance at Dec. 31, 2019		$ 51,975	$ 927,337	$ 882,851	$ (10,226)	$ (6,823)	$ 10,120	$ 1,855,234
Balance (in shares) at Dec. 31, 2019	51,793,923
Increase (Decrease) in Stockholders' Equity
Net income				164,676				164,676
Other comprehensive income, net of tax					72,303			72,303
Cumulative effect of change in accounting principle - ASC 326				1,140				1,140
Dividends declared:
Common, $1.66 per share				(88,484)				(88,484)
Common stock activity under employee stock plans		417	15,375					15,792
Common stock activity under employee stock plans (in shares)	416,614
Stock-based compensation			6,419					6,419
Stock issued for acquisition		1,363	75,579					76,942
Stock issued for acquisition (in shares)	1,363,259
Distribution of stock under deferred compensation arrangements			415			849	(1,264)	0
Distribution of stock under deferred compensation arrangements (in shares)	22,497
Treasury stock purchased						(271)	271	0
Treasury stock purchased (in shares)	(4,406)
Treasury stock issued to benefit plan			38			47		85
Treasury stock issued to benefit plan (in shares)	1,240
Balance at Dec. 31, 2020		53,755	1,025,163	960,183	62,077	(6,198)	9,127	2,104,107
Balance (in shares) at Dec. 31, 2020	53,593,127
Increase (Decrease) in Stockholders' Equity
Net income				189,694				189,694
Other comprehensive income, net of tax					(112,704)			(112,704)
Dividends declared:
Common, $1.66 per share				(91,591)				(91,591)
Common stock activity under employee stock plans		337	9,484					9,821
Common stock activity under employee stock plans (in shares)	337,822
Stock-based compensation			6,334					6,334
Distribution of stock under deferred compensation arrangements			323			694	(1,017)	0
Distribution of stock under deferred compensation arrangements (in shares)	18,089
Treasury stock purchased						(5,106)	252	(4,854)
Treasury stock purchased (in shares)	(70,991)
Balance at Dec. 31, 2021		54,092	1,041,304	1,058,286	(50,627)	(10,610)	8,362	2,100,807
Balance (in shares) at Dec. 31, 2021	53,878,047
Increase (Decrease) in Stockholders' Equity
Net income				188,081				188,081
Other comprehensive income, net of tax					(635,812)			(635,812)
Dividends declared:
Common, $1.66 per share				(93,915)				(93,915)
Common stock activity under employee stock plans		98	1,086					1,184
Common stock activity under employee stock plans (in shares)	97,779
Stock-based compensation			7,738					7,738
Distribution of stock under deferred compensation arrangements			103			739	(842)	0
Distribution of stock under deferred compensation arrangements (in shares)	14,934
Treasury stock purchased						(16,614)	236	(16,378)
Treasury stock purchased (in shares)	(253,511)
Balance at Dec. 31, 2022		$ 54,190	$ 1,050,231	$ 1,152,452	$ (686,439)	$ (26,485)	$ 7,756	$ 1,551,705
Balance (in shares) at Dec. 31, 2022	53,737,249