Condensed Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 60,558	$ 68,141	$ 127,995	$ 154,069
Other comprehensive income (loss):
Foreign currency translation adjustments, before tax	1,767	(11,984)	4,236	(16,301)
Income tax benefit	6	230	28	260
Foreign currency translation adjustments, net of tax	1,773	(11,754)	4,264	(16,041)
Changes in employee benefit related items:
Amortization of prior service cost	2	6	5	8
Recognized actuarial gain	111	357	254	441
Changes in employee benefit related items	113	363	259	449
Income tax (expense)	(1)	(4)	(2)	(7)
Employee benefit related items, net of tax	112	359	257	442
Other comprehensive income (loss)	1,885	(11,395)	4,521	(15,599)
Comprehensive income	$ 62,443	$ 56,746	$ 132,516	$ 138,470