Debt - Schedule of Interest Expense (Details) - Senior Notes - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
The Notes
Debt Instrument [Line Items]
Contractual interest coupon	$ 11.8	$ 11.8
Amortization of debt issuance costs	0.6	0.6
Total	12.4	12.4
2021 Notes
Debt Instrument [Line Items]
Contractual interest coupon	1.2	2.9
Amortization of debt discount	0.8	1.7
Amortization of debt issuance costs	0.1	0.3
Total	$ 2.1	$ 4.9

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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Amount of amortization expense attributable to debt issuance costs.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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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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