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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- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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Date the debt instrument was offered for sale, in CCYY-MM-DD format.

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Amount of the required periodic payments applied to interest.

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Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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The portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate.

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Debt - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Debt Instrument [Line Items]
Amortization of financing costs	$ 0.5	$ 0.5	$ 1.0	$ 1.0
Long term debt	2,494.0		2,494.0		$ 2,493.7
Debt instrument interest			47.8	$ 49.4
Senior Notes \| Fixed-Rate Senior Notes
Debt Instrument [Line Items]
Book value of fixed rate debt	2,494.0		2,494.0
Long-term debt (fixed-rate debt), fair value	2,741.6		$ 2,741.6
Revolving Credit Facility
Debt Instrument [Line Items]
Debt instrument, maturity date			Aug. 29, 2021
Debt instrument offering date			Jun. 08, 2021
Letter Of Credit
Debt Instrument [Line Items]
Long term debt	23.5		$ 23.5
Unsecured Revolving Credit Facility
Debt Instrument [Line Items]
Debt Instrument, Term			5 years
Long term debt	$ 350.0		$ 350.0