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	111,766	$ 0	0	111,766
Other comprehensive income (loss)	0	0	0	0	(55,595)	(55,595)
Cash dividends paid	0	0	(51,681)	0	0	(51,681)
Share-based compensation	0	12,476	0	0	0	12,476
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 Sep. 30, 2022	5,396	120,381	1,690,813	$ (631,853)	(230,223)	954,514
Ending balance (in shares) at Sep. 30, 2022				12,058,773
Beginning balance at Jun. 30, 2022	5,396	116,596	1,672,000	$ (631,853)	(203,172)	958,967
Beginning balance (in shares) at Jun. 30, 2022				12,058,773
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	0	0	36,048	$ 0	0	36,048
Other comprehensive income (loss)	0	0	0	0	(27,051)	(27,051)
Cash dividends paid	0	0	(17,235)	0	0	(17,235)
Share-based compensation	0	3,785	0	0	0	3,785
Ending balance at Sep. 30, 2022	5,396	120,381	1,690,813	$ (631,853)	(230,223)	954,514
Ending balance (in shares) at Sep. 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	99,227	$ 0	0	99,227
Other comprehensive income (loss)	0	0	0	0	10,153	10,153
Cash dividends paid	0	0	(51,900)	0	0	(51,900)
Share-based compensation	0	7,285	0	0	0	7,285
Non-vested stock issued upon vesting	0	(12,686)	0	$ 12,686	0	0
Non-vested stock issued upon vesting (in shares)				(242,110)
Benefit plans	0	375	0	$ 952	0	1,327
Benefit plans (in shares)				(18,172)
Other	0	(2,242)	0	$ (5,792)	0	(8,034)
Other (in shares)				110,549
Ending balance at Sep. 30, 2023	5,396	116,775	1,750,027	$ (624,007)	(190,535)	1,057,656
Ending balance (in shares) at Sep. 30, 2023				11,909,040
Beginning balance at Jun. 30, 2023	5,396	114,330	1,735,807	$ (624,048)	(177,221)	1,054,264
Beginning balance (in shares) at Jun. 30, 2023				11,909,833
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	0	0	31,543	$ 0	0	31,543
Other comprehensive income (loss)	0	0	0	0	(13,314)	(13,314)
Cash dividends paid	0	0	(17,323)	0	0	(17,323)
Share-based compensation	0	2,519	0	0	0	2,519
Non-vested stock issued upon vesting	0	(67)	0	$ 67	0	0
Non-vested stock issued upon vesting (in shares)				(1,285)
Other	0	(7)	0	$ (26)	0	(33)
Other (in shares)				492
Ending balance at Sep. 30, 2023	$ 5,396	$ 116,775	$ 1,750,027	$ (624,007)	$ (190,535)	$ 1,057,656
Ending balance (in shares) at Sep. 30, 2023				11,909,040