ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Summary of Unrealized Gains (Losses) on Derivative Instruments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Reclassification Adjustment Out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Income tax benefit	$ (7.2)	$ (4.6)	$ (13.8)	$ (10.3)
Interest Rate Contract
Reclassification Adjustment Out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Unrealized gain (loss) on derivative instruments	(3.9)	1.2	(6.0)	1.1
Total reclassified into income	0.1	0.0	0.2	0.0
Income tax benefit	1.0	0.0	1.5	0.0
Amounts reclassified from accumulated other comprehensive income, net of tax	1.1	0.0	1.7	0.0
Unrealized gain (loss) on derivative instruments, net of tax	$ (2.8)	$ 1.2	$ (4.3)	$ 1.1