CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 14,165	$ 11,513	$ 34,273	$ 26,446
Other comprehensive income, net of tax:
Foreign currency translation adjustments, net of $0 tax in the three and nine months ended September 30, 2016 and 2015	(254)	40	(271)	18
Unrealized gain (loss) on marketable securities, net of $0 tax in the three and nine months ended September 30, 2016 and 2015	(145)	20	116	(17)
Amortization of defined benefit pension items, net of tax of $11 and $33 in the three and nine months ended September 30, 2016, respectively, and $18 and $26 in the three and nine months ended September 30, 2015, respectively	41	64	121	92
Total other comprehensive income (loss)	(358)	124	(34)	93
TOTAL COMPREHENSIVE INCOME	$ 13,807	$ 11,637	$ 34,239	$ 26,539