Debt - Schedule of Debt (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Long-term debt	$ 1,700.0	$ 2,123.8
Unaccreted discount and debt issuance costs	(14.1)	(16.8)
Hedge accounting fair value adjustments	(0.7)	20.3
Total	1,685.2	2,127.3
Notional amount of derivatives	1,978.2	1,846.2
Designated derivatives:
Debt Instrument [Line Items]
Notional amount of derivatives	1,795.6	1,672.1
Designated derivatives: \| Fair value hedges: \| Interest rate swap contracts
Debt Instrument [Line Items]
Notional amount of derivatives	300.0	300.0
Senior notes \| 4.500% fixed-rate notes (2024 Notes)
Debt Instrument [Line Items]
Long-term debt	$ 0.0	265.8
Effective interest rate	4.70%
Stated interest rate	4.50%
Senior notes \| 4.350% fixed-rate notes ("2025-I Notes")
Debt Instrument [Line Items]
Long-term debt	$ 0.0	158.0
Effective interest rate	4.47%
Stated interest rate	4.35%
Senior notes \| 1.200% fixed-rate notes ("2025-II Notes")
Debt Instrument [Line Items]
Long-term debt	$ 400.0	400.0
Effective interest rate	1.37%
Stated interest rate	1.20%
Senior notes \| 3.750% fixed-rate notes ("2029 Notes")
Debt Instrument [Line Items]
Long-term debt	$ 500.0	500.0
Effective interest rate	3.86%
Stated interest rate	3.75%
Senior notes \| 2.000% fixed-rate notes ("2030 Notes")
Debt Instrument [Line Items]
Long-term debt	$ 400.0	400.0
Effective interest rate	2.12%
Stated interest rate	2.00%
Senior notes \| 5.950% fixed-rate notes ("2041 Notes")
Debt Instrument [Line Items]
Long-term debt	$ 400.0	$ 400.0
Effective interest rate	6.03%
Stated interest rate	5.95%

Debt Instrument, Derivative Instruments Fair Value Adjustment

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- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

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- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Contractual interest rate for funds borrowed, under the debt agreement.

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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 unamortized debt discount (premium) and debt issuance costs.

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- Definition

Nominal or face amount used to calculate payment on derivative.

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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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