CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 13,192	$ 10,845	$ 29,078	$ 18,078
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments, net of $0 tax in each of the three and six months ended June 30, 2020 and 2019	(30)	(250)	(313)	(272)
Unrealized gain on marketable securities, net of $0 tax in each of the three and six months ended June 30, 2020 and 2019	2,566	257	1,614	591
Amortization of defined benefit pension items, net of tax of $24 and $55 in the three and six months ended June 30, 2020, respectively, and $5 and $9 in the three and six months ended June 30, 2019, respectively	58	18	109	34
Total other comprehensive income	2,594	25	1,410	353
TOTAL COMPREHENSIVE INCOME	$ 15,786	$ 10,870	$ 30,488	$ 18,431