Consolidated Statements of Stockholders' Equity (unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in-Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Common Stock in Treasury [Member]	Total
Balance at Dec. 31, 2020	$ 497	$ 578,082	$ 749,056	$ 417	$ (140,434)	$ 1,187,618
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	0	0	117,575	0	0	117,575
Cash dividends	0	0	(35,614)	0	0	(35,614)
Purchase of treasury shares	0	0	0	0	(14,083)	(14,083)
Net issuance of shares to employee and other stock plans	0	(4,679)	0	0	1,730	(2,949)
Stock-based compensation	0	3,819	0	0	0	3,819
Other comprehensive (loss)	0	0	0	(14,909)	0	(14,909)
Balance at Sep. 30, 2021	497	577,222	831,017	(14,492)	(152,787)	1,241,457
Balance at Jun. 30, 2021	497	576,732	805,722	(9,292)	(148,603)	1,225,056
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	0	0	37,433	0	0	37,433
Cash dividends	0	0	(12,138)	0	0	(12,138)
Purchase of treasury shares	0	0	0	0	(4,212)	(4,212)
Net issuance of shares to employee and other stock plans	0	(73)	0	0	28	(45)
Stock-based compensation	0	563	0	0	0	563
Other comprehensive (loss)	0	0	0	(5,200)	0	(5,200)
Balance at Sep. 30, 2021	497	577,222	831,017	(14,492)	(152,787)	1,241,457
Balance at Dec. 31, 2021	497	576,976	856,203	(23,344)	(159,879)	1,250,453
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	0	0	115,874	0	0	115,874
Cash dividends	0	0	(36,907)	0	0	(36,907)
Purchase of treasury shares	0	0	0	0	(14,713)	(14,713)
Net issuance of shares to employee and other stock plans	0	(3,026)	0	0	1,111	(1,915)
Stock-based compensation	0	3,949	0	0	0	3,949
Other comprehensive (loss)	0	0	0	(160,195)	0	(160,195)
Balance at Sep. 30, 2022	497	577,899	935,170	(183,539)	(173,481)	1,156,546
Balance at Jun. 30, 2022	497	577,345	909,029	(124,781)	(173,534)	1,188,556
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	0	0	38,973	0	0	38,973
Cash dividends	0	0	(12,832)	0	0	(12,832)
Net issuance of shares to employee and other stock plans	0	(116)	0	0	53	(63)
Stock-based compensation	0	670	0	0	0	670
Other comprehensive (loss)	0	0	0	(58,758)	0	(58,758)
Balance at Sep. 30, 2022	$ 497	$ 577,899	$ 935,170	$ (183,539)	$ (173,481)	$ 1,156,546