DEBT - Schedule of Interest Expense (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
DEBT
Contractual interest	$ 6.9	$ 9.9	$ 14.4	$ 19.7
Amortization of debt discount	0.1	0.1	0.3	0.3
Amortization of debt issuance cost.	0.4	0.5	0.7	0.9
Interest expense	7.4	10.5	15.4	20.9
Interest income	(0.1)	(0.5)	(0.8)	(1.0)
Interest expense, net	$ 7.3	$ 10.0	$ 14.6	$ 19.9

Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

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- Definition

Amount of amortization expense attributable to debt issuance costs.

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Amount of the cost of borrowed funds accounted for as interest expense for debt.

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Represents the portion of interest incurred in the period on debt arrangements that was charged against earnings, excluding amortization of debt discount (premium) and financing costs.

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The net amount of nonoperating interest income (expense).

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Amount before accretion (amortization) of purchase discount (premium) of interest income on nonoperating securities.

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