Debt And Credit Facilities - Interest Expense (Details) - Convertible Debt - 2.375% convertible senior notes $ in Millions	12 Months Ended
Dec. 31, 2020 USD ($)
Debt Instrument [Line Items]
Contractual interest expense	$ 7.5
Amortization of debt issuance costs	1.0
Amortization of debt discount	11.0
Total interest expense	$ 19.5

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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