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Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

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Fair value portion of notes payable.

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Derivative Financial Instruments and Fair Value Measurements - Additional Information (Details) € in Millions, $ in Millions	Jun. 30, 2021 EUR (€)	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)	Jun. 30, 2020 EUR (€)	Jun. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fair value measured on a recurring basis
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred compensation plan assets		$ 135.0	$ 119.4
Euro-denominated notes \| Estimate of fair value measurement \| Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value of long-term debt		1,119.9	1,159.1
Euro-denominated notes \| Carrying value \| Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value of long-term debt		$ 1,062.8	$ 1,094.5
Cross-currency swap \| Cash flow hedge
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	€ 202.3					$ 55.4
Fixed annual interest rate	1.256%	1.256%				1.143%
Designated as hedging instrument \| Notes due September 2022 \| Euro-denominated notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt				€ 400.0	$ 473.7
Designated as hedging instrument \| Notes Due June 2026 \| Euro-denominated notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	€ 500.0	$ 589.1