SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Debt Issuance Costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Deferred debt issuance cost	$ 0.8
Unamortized debt issuance expense	4.2	$ 3.5
Amortization of debt issuance costs	$ 0.2
Unamortized debt issuance cost amortization period	4 years 9 months 18 days