COMMITMENTS AND CONTINGENCIES - Business Insurance Recoveries (Details) - Cybersecurity Incident - USD ($) $ in Millions	1 Months Ended	3 Months Ended	6 Months Ended
Sep. 30, 2017	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2018
Accrued Liabilities
Beginning Balance	$ 0.0	$ (27.5)	$ (75.6)	$ (87.5)	$ (75.6)
(Expenses incurred) insurance receivable recorded	(87.5)	0.0	(4.1)	(76.5)
Payments made (received)	0.0	17.8	52.2	88.4
Ending Balance	(87.5)	(9.7)	(27.5)	(75.6)	(9.7)
Insurance Receivable
Beginning Balance	0.0	10.0	35.0	0.0	35.0
(Expenses incurred) insurance receivable recorded	0.0	35.0	10.0	50.0
Payments made (received)	0.0	(45.0)	(35.0)	(15.0)
Ending Balance	$ 0.0	$ 0.0	$ 10.0	$ 35.0	$ 0.0

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Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities.

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The increase (decrease) during the reporting period in the aggregate amount of expenses incurred but not yet paid.

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The increase (decrease) during the reporting period in insurance settlements receivable, which are amounts due in settlement of a claim for reimbursement from an insurance company when the Company has suffered a loss covered under an insurance policy. The expectation is that such reimbursement will be received within one year of the balance sheet date.

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Amount due in settlement of a claim for reimbursement from an insurance company when the Company has suffered a loss covered under an insurance policy.

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The amount of loss pertaining to the specified contingency that was charged against earnings in the period, including the effects of revisions in previously reported estimates.

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