GOODWILL (Goodwill Roll Forward) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Goodwill [Roll Forward]
Balance as of January 1, 2019	$ 166,832
Effect of net foreign currency exchange rate changes	875
Balance as of March 31, 2019	167,707
North America
Goodwill [Roll Forward]
Balance as of January 1, 2019	103,542
Effect of net foreign currency exchange rate changes	0
Balance as of March 31, 2019	103,542
Europe
Goodwill [Roll Forward]
Balance as of January 1, 2019	63,290
Effect of net foreign currency exchange rate changes	875
Balance as of March 31, 2019	$ 64,165