INCOME TAXES - Income tax expense (benefit), income tax reconciliation and components of deferred tax assets and liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income tax provision (benefit), income tax reconciliation [Abstract]
U.K. statutory rate	20.00%	20.25%	21.50%
Tax at statutory rate	$ 65.1	$ 31.9	$ (58.0)
Capitalized interest transactions	0.0	(5.7)	(20.1)
Tax audit settlements	0.0	0.0	10.4
Foreign rate differential	(92.7)	(30.0)	38.2
Deferred intercompany gain/loss	(20.1)	(33.8)	(86.6)
Foreign asset basis difference	405.9	0.0	0.0
Luxembourg restructuring operating loss	(1,180.2)	0.0	0.0
Change in valuation allowance	814.7	106.0	(3.6)
Prior period adjustments	(4.1)	(6.9)	7.5
Unrecognized tax benefits	7.1	9.7	(35.8)
U.S. tax on RCI non-U.S. subsidiaries	6.3	0.0	0.0
Termination of local country activity	0.0	(6.3)	0.0
Foreign tax credits/deductions	(1.5)	(2.2)	(4.9)
Other, net	4.5	1.7	2.2
Total provision (benefit)	5.0	64.4	$ (150.7)
Deferred tax assets
Accrued employee benefit plan costs	81.1	137.9
U.S. net operating loss	111.2	27.5
Interest expense limitation carryforward	0.0	42.1
Other NOLs and tax credit carryforwards	36.8	33.1
Other	31.2	30.6
Total deferred tax assets	1,453.7	281.7
Less: valuation allowance	889.8	128.3
Deferred tax assets, net of valuation allowance	563.9	153.4
Deferred tax liabilities
Property and equipment	712.8	296.6
Other	12.3	52.6
Total deferred tax liabilities	725.1	349.2
Net deferred tax asset (liability)	(161.2)	(195.8)
U.K. [Member]
Deferred tax assets
Foreign net operating loss	2.8	2.8
Trinidad [Member]
Deferred tax assets
Foreign net operating loss	6.5	7.7
Luxembourg [Member]
Deferred tax assets
Foreign net operating loss	1,180.2	0.0
Less: valuation allowance	747.0
Suriname [Member]
Deferred tax assets
Foreign net operating loss	$ 3.9	$ 0.0