OPERATING SEGMENTS - Revenue and Long-lived Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Revenue and Long-Lived Assets Outside of the United States
Total revenue	$ 126,057	$ 122,351	$ 236,291	$ 235,669
Total long- lived assets	460,084		460,084		$ 460,593
United States
Revenue and Long-Lived Assets Outside of the United States
Total revenue	110,763	111,183	206,955	214,374
Total long- lived assets	403,448		403,448		405,767
Canada
Revenue and Long-Lived Assets Outside of the United States
Total revenue	15,294	$ 11,168	29,336	$ 21,295
Total long- lived assets	$ 56,636		$ 56,636		$ 54,826