Accounting policies.

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Draw on revolving credit facility

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Percentage of goodwill over fair value of reporting unit.

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Value of input used to measure alternative investment.

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This element represents disclosure of the aggregate cash dividends paid to the entity by unconsolidated subsidiaries.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Basis of Presentation and Accounting Policies - Additional Information (Details) $ in Millions		3 Months Ended		9 Months Ended
	Oct. 01, 2021 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Accounting Policies [Line Items]
Non-cash impairment charge loss		$ 0.0	$ 0.0	$ 0.0	$ 66.8
Goodwill		$ 1,206.6		$ 1,206.6		$ 1,225.8
NETHERLANDS
Accounting Policies [Line Items]
Percentage of goodwill over fair value of reporting unit				5.50%
Ettain Group [Member] \| Subsequent Event [Member]
Accounting Policies [Line Items]
Aggregate cash consideration paid	$ 930.9
Draw on revolving credit facility	150.0
Ettain Group [Member] \| working capital and cash [Member] \| Subsequent Event [Member]
Accounting Policies [Line Items]
Aggregate cash consideration paid	5.9
Ettain Group [Member] \| Acquired interests [Member] \| Subsequent Event [Member]
Accounting Policies [Line Items]
Aggregate cash consideration paid	$ 925.0
Netherlands \| Discount Rates
Accounting Policies [Line Items]
Percentage of goodwill over fair value of reporting unit				10.40%
Netherlands \| Terminal Value Revenue Growth Rate
Accounting Policies [Line Items]
Discount rate for goodwill impairment test (as a percent)		2.0		2.0
Netherlands \| Terminal Value OUP Margin
Accounting Policies [Line Items]
Discount rate for goodwill impairment test (as a percent)		3.5		3.5
Northern Europe \| United Kingdom
Accounting Policies [Line Items]
Goodwill		$ 110.3		$ 110.3		100.2
Northern Europe \| Netherlands
Accounting Policies [Line Items]
Goodwill		$ 114.2		$ 114.2		$ 119.3
Minimum
Accounting Policies [Line Items]
Percentage of goodwill over fair value of reporting unit				20.00%
Minimum \| Other Reporting Units
Accounting Policies [Line Items]
Percentage of goodwill over fair value of reporting unit				20.00%
Minimum \| Netherlands \| Terminal Value Revenue Growth Rate
Accounting Policies [Line Items]
Discount rate for goodwill impairment test (as a percent)		3.0		3.0
Maximum [Member] \| Netherlands \| Terminal Value Revenue Growth Rate
Accounting Policies [Line Items]
Discount rate for goodwill impairment test (as a percent)		5.0		5.0