Condensed Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 68,141	$ 90,917	$ 154,069	$ 172,004
Other comprehensive (loss) income:
Foreign currency translation adjustments, before tax	(11,984)	809	(16,301)	(1,923)
Income tax benefit (expense)	230	21	260	(9)
Foreign currency translation adjustments, net of tax	(11,754)	830	(16,041)	(1,932)
Changes in employee benefit related items:
Amortization of prior service cost	6	4	8	2
Recognized actuarial gain (loss)	357	212	441	(62)
Changes in employee benefit related items	363	216	449	(60)
Income tax (expense) benefit	(4)	(1)	(7)	1
Employee benefit (expense) related items, net of tax	359	215	442	(59)
Other comprehensive (loss) income	(11,395)	1,045	(15,599)	(1,991)
Comprehensive income	$ 56,746	$ 91,962	$ 138,470	$ 170,013