INCOME TAXES - Narrative (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended			12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	[1]	Sep. 30, 2018	Sep. 30, 2017	[1]	Dec. 31, 2017
Income Tax Disclosure [Line Items]
Benefit from income taxes	$ (38.7)	$ (10.8)		$ (43.1)	$ (37.8)
Increase (Decrease) in Income Tax Expense (Benefit)	$ (27.9)			$ (5.3)
Impact of Tax Cuts and Jobs Act							$ 47.9
Domestic [Member]
Income Tax Disclosure [Line Items]
Tax loss carryforwards							$ 519.3

[1] Adjusted as a result of the adoption of certain accounting pronouncements during 2018. See Note 1, "Description of Business and Summary of Significant Accounting Policies - Recently Adopted Accounting Pronouncements," for details of these adjustments.