INCOME TAXES - Components of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current income tax expense:
Federal	$ (9,097)	$ (5,817)	$ (4,485)
State	(511)	(54)	(47)
Foreign	(8,677)	(15,406)	(12,902)
Current income tax benefit (expense)	(18,285)	(21,277)	(17,434)
Deferred income tax (expense) benefit:
Federal	12,622	(24,425)	(2,683)
State	611	(23)	(503)
Foreign	(419)	73	92
Deferred income tax expense, gross	12,814	(24,375)	(3,094)
Income tax expense	$ (5,471)	$ (45,652)	$ (20,528)