INCOME TAXES - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
U.K. Enacted statutory income tax rate, Jan 1, 2014 - Mar 31, 2017		20.00%
U.K. Enacted statutory income tax rate, Apr 1, 2017 - Mar 31, 2020		19.00%
U.K. Enacted statutory income tax rate, beginning Apr 1, 2020		17.00%
U.K. statutory rate		19.00%	19.25%	20.00%
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Valuation allowance	$ 869.9	$ 905.9	$ 869.9
Deferred tax valuation allowance increase (decrease)			(52.1)
Provisional amount resulting from the remeasurement of deferred tax assets			(56.7)
Unrecognized tax benefits, net	41.0	35.0	41.0	$ 59.0
Tax impact of unrecognized tax benefits, if reversed		35.0
Accrued interest on income taxes	1.4	1.7	1.4	11.8
Accrued penalties on income taxes	2.2	(0.5)	2.2	3.1
IRS proposed unfavorable tax adjustments		85.0
Luxembourg [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Net operating loss carryforwards				4,534.0
Valuation allowance	766.5	867.9	766.5	$ 747.0
Deferred tax valuation allowance increase (decrease)		101.4	19.8
Operating loss carryforwards subject to valuation allowance		3,337.0
Non expiring NOLs		4,803.0
U.S. [Member]
Operating Loss Carryforwards [Line Items]
Provisional amount relating to the one-time transition tax on certain previously deferred non-U.S. earnings	34.1	26.4
Provision expense resulting from change in tax rate	56.7	61.6
Increase (Decrease) In Income Tax Expense		4.9
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Net operating loss carryforwards		366.0
Valuation allowance	90.4	22.0	90.4
Deferred tax valuation allowance increase (decrease)		(68.4)	(41.7)
Operating loss carryforwards subject to valuation allowance		76.0
U.K. [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Operating loss carryforwards subject to valuation allowance		36.0
Non expiring NOLs		36.0
Trinidad [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Operating loss carryforwards subject to valuation allowance		21.0
Non expiring NOLs		21.0
Foreign [Member]
Operating Loss Carryforwards [Line Items]
Provision expense resulting from change in tax rate	$ 38.3	33.7
Increase (Decrease) In Income Tax Expense		(12.3)
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Valuation allowance		906.0
Non expiring NOLs		15.0
Non expiring NOLs subject to a valuation allowance		15.0
Tax credit carryforward		$ 29.0
Deferred Intra-Entity Transfer Asset [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Deferred tax valuation allowance increase (decrease)			$ 60.3