CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Earnings Reinvested in the Business [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Beginning balance at Dec. 31, 2021	$ 5,396	$ 111,352	$ 1,630,713	$ (634,408)	$ (174,628)	$ 938,425
Beginning balance (in shares) at Dec. 31, 2021				12,107,549
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	0	0	75,718	$ 0	0	75,718
Other comprehensive income (loss)	0	0	0	0	(28,544)	(28,544)
Cash dividends paid	0	0	(34,446)	0	0	(34,446)
Share-based compensation	0	8,691	0	0	0	8,691
Non-vested stock issued upon vesting	0	(3,239)	0	$ 3,239	0	0
Non-vested stock issued upon vesting (in shares)				(61,821)
Benefit plans	0	560	0	$ 618	0	1,178
Benefit plans (in shares)				(11,786)
Other	0	(768)	15	$ (1,302)	0	(2,055)
Other (in shares)				24,831
Ending balance at Jun. 30, 2022	5,396	116,596	1,672,000	$ (631,853)	(203,172)	958,967
Ending balance (in shares) at Jun. 30, 2022				12,058,773
Beginning balance at Mar. 31, 2022	5,396	112,973	1,650,588	$ (632,382)	(174,865)	961,710
Beginning balance (in shares) at Mar. 31, 2022				12,068,868
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	0	0	38,647	$ 0	0	38,647
Other comprehensive income (loss)	0	0	0	0	(28,307)	(28,307)
Cash dividends paid	0	0	(17,235)	0	0	(17,235)
Share-based compensation	0	4,528	0	0	0	4,528
Non-vested stock issued upon vesting	0	(761)	0	$ 761	0	0
Non-vested stock issued upon vesting (in shares)				(14,523)
Other	0	(144)	0	$ (232)	0	(376)
Other (in shares)				4,428
Ending balance at Jun. 30, 2022	5,396	116,596	1,672,000	$ (631,853)	(203,172)	958,967
Ending balance (in shares) at Jun. 30, 2022				12,058,773
Beginning balance at Dec. 31, 2022	5,396	124,043	1,702,700	$ (631,853)	(200,688)	999,598
Beginning balance (in shares) at Dec. 31, 2022				12,058,773
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	0	0	67,684	$ 0	0	67,684
Other comprehensive income (loss)	0	0	0	0	23,467	23,467
Cash dividends paid	0	0	(34,577)	0	0	(34,577)
Share-based compensation	0	4,766	0	0	0	4,766
Non-vested stock issued upon vesting	0	(12,619)	0	$ 12,619	0	0
Non-vested stock issued upon vesting (in shares)				(240,825)
Benefit plans	0	375	0	$ 952	0	1,327
Benefit plans (in shares)				(18,172)
Other	0	(2,235)	0	$ (5,766)	0	(8,001)
Other (in shares)				110,057
Ending balance at Jun. 30, 2023	5,396	114,330	1,735,807	$ (624,048)	(177,221)	1,054,264
Ending balance (in shares) at Jun. 30, 2023				11,909,833
Beginning balance at Mar. 31, 2023	5,396	112,589	1,719,096	$ (624,473)	(184,387)	1,028,221
Beginning balance (in shares) at Mar. 31, 2023				11,917,944
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	0	0	34,033	$ 0	0	34,033
Other comprehensive income (loss)	0	0	0	0	7,166	7,166
Cash dividends paid	0	0	(17,322)	0	0	(17,322)
Share-based compensation	0	2,499	0	0	0	2,499
Non-vested stock issued upon vesting	0	(663)	0	$ 663	0	0
Non-vested stock issued upon vesting (in shares)				(12,644)
Other	0	(95)	0	$ (238)	0	(333)
Other (in shares)				4,533
Ending balance at Jun. 30, 2023	$ 5,396	$ 114,330	$ 1,735,807	$ (624,048)	$ (177,221)	$ 1,054,264
Ending balance (in shares) at Jun. 30, 2023				11,909,833