CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME [Abstract]
NET INCOME	$ 21,361	$ 11,777	$ 36,760	$ 16,903
OTHER COMPREHENSIVE (LOSS) INCOME, NET OF TAX:
Defined benefit pension plan adjustments	324		571
Foreign currency translation adjustment	(258)	(1,146)	672	(1,734)
Unrealized loss in fair value of investments	(153)	(74)	(145)	(84)
Unrealized gain (loss) in fair value of interest rate swap	11	60	(24)	105
Total other comprehensive (loss) income, net of tax	(76)	(1,160)	1,074	(1,713)
TOTAL COMPREHENSIVE INCOME	$ 21,285	$ 10,617	$ 37,834	$ 15,190