ACCUMULATED OTHER COMPREHENSIVE LOSS - Reclassification out of Accumulated Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance			$ (614.8)
Ending balance	$ (672.4)		(672.4)
Interest rate swap
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Ending balance	(1.8)		(1.8)
Deferred gain - hedging
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance			(3.0)
Ending balance	(1.8)		(1.8)
Deferred gain - hedging | Interest rate swap
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(2.4)	$ (4.7)	(3.0)	$ (3.8)
Ending balance	(1.8)	(4.5)	(1.8)	(4.5)
Deferred gain - hedging | Interest rate swap | Reclassification out of Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Change in fair value, net of tax		(0.5)		(2.0)
Other Comprehensive Income (Loss), Tax [Abstract]
Change in fair value - tax expense (benefit)		0.3		1.2
Deferred gain - hedging | Interest rate swap | Interest Expense | Reclassification out of Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Reclassifications into earnings, net of tax	0.6	0.7	1.2	1.3
Other Comprehensive Income (Loss), Tax [Abstract]
Reclassifications into earnings - tax expense (benefit)	$ 0.3	$ 0.4	$ 0.7	$ (0.8)