CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 11,265	$ 8,590	$ 20,108	$ 14,933
Other comprehensive income, net of tax:
Foreign currency translation adjustments, net of $0 tax in the three and six months ended June 30, 2016 and 2015	37	(57)	(17)	(22)
Unrealized gain (loss) on marketable securities, net of $0 tax in the three and six months ended June 30, 2016 and 2015	48	(93)	261	(37)
Amortization of defined benefit pension items, net of tax of $11 and $22 in the three and six months ended June 30, 2016, respectively, and $4 and $8 in the three and six months ended June 30, 2015, respectively	40	14	80	28
Total other comprehensive income (loss)	125	(136)	324	(31)
TOTAL COMPREHENSIVE INCOME	$ 11,390	$ 8,454	$ 20,432	$ 14,902