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Acquisitions Acquisition Costs, by Acquisition (Details) - USD ($) $ in Millions		12 Months Ended
	Apr. 02, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross		$ 186.0	$ 113.0
Goodwill		1,618.4	1,486.9
Revenues		3,950.6	3,923.9	$ 3,399.8
Apex
Business Acquisition [Line Items]
Revenues		2,421.2	2,520.0	2,300.3
ECS
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	$ 775.0
Business Acquisition, Transaction Costs	12.0
Goodwill	528.2
Revenues		$ 1,004.2	$ 798.2	493.0
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual				$ 14.2
Business Acquisition, Goodwill, Expected Tax Deductible Amount	514.2
Identifiable intangible assets	$ 195.0
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	11 years

X

- Definition

Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of direct costs of the business combination including legal, accounting, and other costs incurred to consummate the business acquisition.

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The amount of goodwill arising from a business combination that is expected to be deductible for tax purposes.

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This element represents the amount of earnings or loss of the acquiree since the acquisition date included in the consolidated income statement for the reporting period.

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Amount of assets, excluding financial assets and goodwill, that lack physical substance, having a projected indefinite period of benefit, acquired at the acquisition date.

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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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The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

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