ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Changes in AOCI (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Accumulated other comprehensive income (loss)
Balance at the beginning	$ 324,077
Balance at the end	340,300
Foreign Currency Translation
Accumulated other comprehensive income (loss)
Balance at the beginning	(8,603)
Other comprehensive income before reclassifications, net of tax	(3,468)
Other comprehensive income, net	(3,468)
Balance at the end	(12,071)
Unrealized Gain (Loss) on Interest Rate Hedge
Accumulated other comprehensive income (loss)
Balance at the beginning	(501)
Other comprehensive income before reclassifications, net of tax	1,913
Amounts reclassified out of AOCI, net of tax	310
Other comprehensive income, net	2,223
Balance at the end	1,722
Accumulated Other Comprehensive Income (Loss)
Accumulated other comprehensive income (loss)
Balance at the beginning	(9,104)
Other comprehensive income before reclassifications, net of tax	(1,555)
Amounts reclassified out of AOCI, net of tax	310
Other comprehensive income, net	(1,245)
Balance at the end	$ (10,349)