BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) - Blackstone - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Transactions with Affiliates
Expenses incurred for services from subsidiaries	$ 0.3	$ 0.1	$ 1.3	$ 0.5
Blackstone Capital Partners VI L.P.
Transactions with Affiliates
Beneficial ownership (shares)	6,896,548		6,896,548

Balance held at close of period in number of shares.

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