Consolidated Statements of Changes in 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	Cumulative Effect Adjustment for ASU Implementation [Member] Common Stock [Member]	Cumulative Effect Adjustment for ASU Implementation [Member] Additional Paid-in-Capital [Member]	Cumulative Effect Adjustment for ASU Implementation [Member] Retained Earnings [Member]	Cumulative Effect Adjustment for ASU Implementation [Member] Accumulated Other Comprehensive (Loss) Income [Member]	Cumulative Effect Adjustment for ASU Implementation [Member] Common Stock in Treasury [Member]	Cumulative Effect Adjustment for ASU Implementation [Member]
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	76,901	0	0	76,901
Cash dividends	0	0	(24,075)	0	0	(24,075)
Purchase of treasury shares	0	0	0	0	(14,713)	(14,713)
Net issuance of shares to employee and other stock plans	0	(2,910)	0	0	1,058	(1,852)
Stock-based compensation	0	3,279	0	0	0	3,279
Other comprehensive (loss)	0	0	0	(101,437)	0	(101,437)
Balance at Jun. 30, 2022	497	577,345	909,029	(124,781)	(173,534)	1,188,556
Balance at Mar. 31, 2022	497	577,374	883,246	(91,375)	(167,492)	1,202,250
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	0	0	37,775	0	0	37,775
Cash dividends	0	0	(11,992)	0	0	(11,992)
Purchase of treasury shares	0	0	0	0	(6,561)	(6,561)
Net issuance of shares to employee and other stock plans	0	(836)	0	0	519	(317)
Stock-based compensation	0	807	0	0	0	807
Other comprehensive (loss)	0	0	0	(33,406)	0	(33,406)
Balance at Jun. 30, 2022	497	577,345	909,029	(124,781)	(173,534)	1,188,556
Balance at Dec. 31, 2022	497	577,853	958,433	(190,034)	(173,195)	1,173,554
Balance (ASU 2022-02 [Member]) at Dec. 31, 2022							$ 0	$ 0	$ 502	$ 0	$ 0	$ 502
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	0	0	63,730	0	0	63,730
Cash dividends	0	0	(25,745)	0	0	(25,745)
Purchase of treasury shares	0	0	0	0	(2,778)	(2,778)
Net issuance of shares to employee and other stock plans	0	(2,843)	0	0	827	(2,016)
Stock-based compensation	0	3,312	0	0	0	3,312
Other comprehensive (loss)	0	0	0	(66)	0	(66)
Balance at Jun. 30, 2023	497	578,322	996,920	(190,100)	(175,146)	1,210,493
Balance at Mar. 31, 2023	497	577,952	979,722	(173,918)	(172,594)	1,211,659
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	0	0	30,072	0	0	30,072
Cash dividends	0	0	(12,874)	0	0	(12,874)
Purchase of treasury shares	0	0	0	0	(2,778)	(2,778)
Net issuance of shares to employee and other stock plans	0	(477)	0	0	226	(251)
Stock-based compensation	0	847	0	0	0	847
Other comprehensive (loss)	0	0	0	(16,182)	0	(16,182)
Balance at Jun. 30, 2023	$ 497	$ 578,322	$ 996,920	$ (190,100)	$ (175,146)	$ 1,210,493