REVENUE FROM CONTRACTS WITH CUSTOMERS , CONTRACT ASSETS AND LIABILITIES (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Change in Contract with Customer, Liability [Roll Forward]
Beginning balance	$ 51,459
Revenue recognized in the current period from the amounts in the beginning balance	(30,015)
New deferrals, net of amounts recognized in the current period	38,723
Effects of foreign currency	134
Ending balance	60,301
Current liability	56,155	$ 51,459
Noncurrent liability	$ 4,000