CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 45,964	$ 42,034	$ 148,036	$ 123,713
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments, net of $0 tax in each of the three and nine months ended September 30, 2022 and 2021	(1,044)	(154)	(2,067)	(212)
Unrealized gain (loss) on marketable securities, net of $0 tax in each of the three and nine months ended September 30, 2022 and 2021	(731)	7	(6,072)	(904)
Amortization of defined benefit pension items, net of tax of $3 and $6 in the three and nine months ended September 30, 2022, respectively, and $6 and $147 in the three and nine months ended September 30, 2021, respectively	18	53	59	30
Total other comprehensive loss	(1,757)	(94)	(8,080)	(1,086)
TOTAL COMPREHENSIVE INCOME	$ 44,207	$ 41,940	$ 139,956	$ 122,627