CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock	Deferred Compensation Arrangements	Total
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			86,860				86,860
Other comprehensive loss, net of tax				(468,100)			(468,100)
Dividends declared:
Common			(46,482)				(46,482)
Common stock activity under employee stock plans	$ 93	706					799
Common stock activity under employee stock plans (in shares)	92,695
Stock-based compensation		4,190					4,190
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					(16,378)		(16,378)
Treasury stock purchased (in shares)	(250,000)
Treasury stock issued to benefit plans, net					(120)	120	0
Treasury stock issued to benefit plans, net (in shares)	(1,649)
Balance at Jun. 30, 2022	$ 54,185	1,046,303	1,098,664	(518,727)	(26,369)	7,640	1,661,696
Balance (in shares) at Jun. 30, 2022	53,734,027
Balance at Mar. 31, 2022	$ 54,164	1,043,707	1,082,107	(321,994)	(13,464)	7,583	1,852,103
Balance (in shares) at Mar. 31, 2022	53,913,362
Increase (Decrease) in Stockholders' Equity
Net income			39,805				39,805
Other comprehensive loss, net of tax				(196,733)			(196,733)
Dividends declared:
Common			(23,248)				(23,248)
Common stock activity under employee stock plans	$ 21	293					314
Common stock activity under employee stock plans (in shares)	21,481
Stock-based compensation		2,304					2,304
Distribution of stock under deferred compensation arrangements		(1)			1		0
Distribution of stock under deferred compensation arrangements (in shares)	20
Treasury stock purchased					(12,849)		(12,849)
Treasury stock purchased (in shares)	(200,000)
Treasury stock issued to benefit plans, net					(57)	57	0
Treasury stock issued to benefit plans, net (in shares)	(836)
Balance at Jun. 30, 2022	$ 54,185	1,046,303	1,098,664	(518,727)	(26,369)	7,640	1,661,696
Balance (in shares) at Jun. 30, 2022	53,734,027
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
Increase (Decrease) in Stockholders' Equity
Net income			54,089				54,089
Other comprehensive loss, net of tax				74,737			74,737
Dividends declared:
Common			(47,415)				(47,415)
Common stock activity under employee stock plans	$ 174	490					664
Common stock activity under employee stock plans (in shares)	173,539
Stock-based compensation		4,194					4,194
Distribution of stock under deferred compensation arrangements		(44)			1,126	(1,082)	0
Distribution of stock under deferred compensation arrangements (in shares)	19,264
Treasury stock purchased					(20,568)		(20,568)
Treasury stock purchased (in shares)	(400,000)
Treasury stock issued to benefit plans, net					(111)	111	0
Treasury stock issued to benefit plans, net (in shares)	(1,962)
Balance at Jun. 30, 2023	$ 54,364	1,054,871	1,159,126	(611,702)	(46,038)	6,785	1,617,406
Balance (in shares) at Jun. 30, 2023	53,528,090
Balance at Mar. 31, 2023	$ 54,360	1,052,802	1,134,527	(578,085)	(36,325)	6,734	1,634,013
Balance (in shares) at Mar. 31, 2023	53,724,917
Increase (Decrease) in Stockholders' Equity
Net income			48,291				48,291
Other comprehensive loss, net of tax				(33,617)			(33,617)
Dividends declared:
Common			(23,692)				(23,692)
Common stock activity under employee stock plans	$ 4	147					151
Common stock activity under employee stock plans (in shares)	4,206
Stock-based compensation		1,922					1,922
Treasury stock purchased					(9,662)		(9,662)
Treasury stock purchased (in shares)	(200,000)
Treasury stock issued to benefit plans, net					(51)	51	0
Treasury stock issued to benefit plans, net (in shares)	(1,033)
Balance at Jun. 30, 2023	$ 54,364	$ 1,054,871	$ 1,159,126	$ (611,702)	$ (46,038)	$ 6,785	$ 1,617,406
Balance (in shares) at Jun. 30, 2023	53,528,090