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Goodwill and Identifiable Assets Acquired Intangible Assets (Details) - USD ($) $ in Millions		12 Months Ended
	Apr. 02, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Intangible Assets [Line Items]
Amortization of intangible assets		$ 51.7	$ 51.1	$ 58.5
Identifiable intangible assets, net		487.9	476.5
Intangible Assets, Gross (Excluding Goodwill)		828.5	764.7
Intangible assets subject to amortization:
Gross Carrying Amount		569.6	505.8
Accumulated Amortization		340.6	288.2
Net Carrying Amount		229.0	217.6
Intangible assets not subject to amortization:
Trademarks, Carrying Amount		258.9	258.9
Minimum [Member]
Intangible assets not subject to amortization:
Finite-Lived Intangible Asset, Useful Life	4 years
Maximum [Member]
Intangible assets not subject to amortization:
Finite-Lived Intangible Asset, Useful Life	7 years
Other Acquisitions
Intangible assets subject to amortization:
Gross Carrying Amount		$ 62.9
Intangible assets not subject to amortization:
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		7 years 6 months
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		7 years 6 months
2019 Acquisitions
Intangible assets subject to amortization:
Gross Carrying Amount			$ 42.8
Intangible assets not subject to amortization:
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			10 years 6 months
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			10 years 6 months
Contractual customer relationships
Intangible assets subject to amortization:
Gross Carrying Amount		$ 441.3	$ 384.9
Accumulated Amortization		222.9	179.9
Net Carrying Amount		$ 218.4	205.0
Contractual customer relationships \| Minimum [Member]
Intangible assets not subject to amortization:
Finite-Lived Intangible Asset, Useful Life		7 years 3 months 18 days
Contractual customer relationships \| Maximum [Member]
Intangible assets not subject to amortization:
Finite-Lived Intangible Asset, Useful Life		12 years 9 months
Contractor relations
Intangible assets subject to amortization:
Gross Carrying Amount		$ 71.2	71.1
Accumulated Amortization		71.0	70.6
Net Carrying Amount		0.2	0.5
Backlog
Intangible assets subject to amortization:
Gross Carrying Amount		29.3	25.0
Accumulated Amortization		28.5	23.9
Net Carrying Amount		$ 0.8	1.1
Backlog \| Minimum [Member]
Intangible assets not subject to amortization:
Finite-Lived Intangible Asset, Useful Life		1 year
Backlog \| Maximum [Member]
Intangible assets not subject to amortization:
Finite-Lived Intangible Asset, Useful Life		2 years 9 months
Non-compete agreements
Intangible assets subject to amortization:
Gross Carrying Amount		$ 27.8	24.8
Accumulated Amortization		18.2	13.8
Net Carrying Amount		$ 9.6	$ 11.0
Non-compete agreements \| Minimum [Member]
Intangible assets not subject to amortization:
Finite-Lived Intangible Asset, Useful Life		4 years
Non-compete agreements \| Maximum [Member]
Intangible assets not subject to amortization:
Finite-Lived Intangible Asset, Useful Life		7 years