SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2019	Jan. 01, 2018	Jan. 01, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle in period of adoption		$ 741,557	$ 787,882	$ 933,562	$ 279,816
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201609Member	us-gaap:AccountingStandardsUpdate201409	us-gaap:AccountingStandardsUpdate201409Member	us-gaap:AccountingStandardsUpdate201609Member
Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle in period of adoption			$ 1,136	$ 21,558		$ 1,100	$ 21,600