EQUITY COMPENSATION (Restricted Units) (Details) $ / shares in Units, $ in Millions					3 Months Ended								12 Months Ended
	Nov. 17, 2017 $ / shares	Aug. 18, 2017 $ / shares	May 30, 2017 $ / shares	Mar. 10, 2017 $ / shares	Dec. 31, 2017 USD ($) $ / shares shares	Sep. 30, 2017 $ / shares	Jun. 30, 2017 $ / shares	Mar. 31, 2017 $ / shares shares	Dec. 31, 2016 $ / shares shares	Sep. 30, 2016 $ / shares	Jun. 30, 2016 $ / shares	Mar. 31, 2016 $ / shares	Dec. 31, 2017 USD ($) quarter $ / shares shares
Equity compensation
Number of quarterly distributions declared | quarter													4
Quarterly distribution declared (in dollars per unit)	$ 0.41	$ 0.31	$ 0.13	$ 0.28	$ 0.25	$ 0.41	$ 0.31	$ 0.13	$ 0.28	$ 0.20	$ 0.28	$ 0.15
Distribution equivalents made to holders | $													$ 16.0
Restricted units
Units
Balance at the beginning of the period (in units) | shares								8,058,372					8,058,372
Granted (in units) | shares													7,999,669
Vested (in units) | shares													(1,843,730)
Forfeited (in units) | shares													(462,423)
Balance at the end of the period (in units) | shares					13,751,888				8,058,372				13,751,888
Weighted Average Grant Date Fair Value
Balance at the beginning of the period (in dollars per unit)								$ 16.38					$ 16.38
Granted (in dollars per unit)													18.60
Vested (in dollars per unit)													16.57
Forfeited (in dollars per unit)													18.19
Balance at the end of the period (in dollars per unit)					$ 17.58				$ 16.38				$ 17.58
Unrecognized compensation expenses | $					$ 169.5								$ 169.5
Weighted average period of compensation expense expected to be recognized													3 years 5 months 26 days