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Business Acquisitions and Disposition (Details) $ in Millions		9 Months Ended
	Mar. 17, 2021 USD ($)	Sep. 30, 2021 USD ($) acquisition	Dec. 31, 2020 USD ($)
Business Acquisition [Line Items]
Number of business acquisitions \| acquisition		4
Goodwill		$ 13,989.2	$ 13,966.0
Sedaru, Inc.
Business Acquisition [Line Items]
Sale of investment	$ 27.1
Pretax gain on sale of investment	$ 27.1
Other acquisitions
Business Acquisition [Line Items]
Purchase price		19.7
Goodwill		13.6
Intangible assets acquired		8.3
Other acquisitions \| Customer related intangibles
Business Acquisition [Line Items]
Intangible assets acquired		$ 8.0
Weighted average useful life of intangible assets acquired		13 years 7 months 6 days
Other acquisitions \| Technology
Business Acquisition [Line Items]
Intangible assets acquired		$ 0.3
Weighted average useful life of intangible assets acquired		5 years