SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Changes in Cash Flows Due to Adoption of ASU 2016-15 (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net cash provided by operating activities	$ 101,647	$ 31,587
Net decrease in balance	(529,124)	(12,721)
Balance	$ 58,170	21,965	$ 587,449	$ 34,665
As Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net cash provided by operating activities		31,438
Net decrease in balance		(12,870)
Balance		$ 12,814		$ 25,663