INCOME TAXES - Summary of Changes in Deferred Tax Asset Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Tax Assets [Roll Forward]
Balance, January 1,	$ 142,749	$ 132,712	$ 164,865
Increase in deferred tax assets	31,092	10,037	27,183
Remeasurement in deferred tax assets	0	0	(59,336)
Balance, December 31,	$ 173,841	$ 142,749	$ 132,712