Goodwill and Identifiable Assets (Acquired Intangible Assets) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Intangible assets subject to amortization:
Gross Carrying Amount	$ 603.3	$ 603.6
Accumulated Amortization	371.9	358.3
Net Carrying Amount	231.4	245.3
Intangible assets not subject to amortization:
Trademarks, Carrying Amount	242.6	242.6
Intangible Assets, Gross (Excluding Goodwill)	845.9	846.2
Intangible Assets, Net (Excluding Goodwill), Total	474.0	487.9
Customer and Contractual Relationships
Intangible assets subject to amortization:
Accumulated Amortization	272.0	260.2
Net Carrying Amount	221.8	233.7
Total
Other Finite-Lived Intangible Assets, Gross	$ 493.8	493.9
Customer and Contractual Relationships | Minimum [Member]
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	7 years
Customer and Contractual Relationships | Maximum [Member]
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	13 years
Contractor Relations
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	4 years
Intangible assets subject to amortization:
Accumulated Amortization	$ 45.4	45.5
Net Carrying Amount	0.0	0.0
Total
Other Finite-Lived Intangible Assets, Gross	45.4	45.5
Backlog
Intangible assets subject to amortization:
Accumulated Amortization	31.9	31.0
Net Carrying Amount	2.8	3.8
Total
Other Finite-Lived Intangible Assets, Gross	$ 34.7	34.8
Backlog | Minimum [Member]
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	1 year
Backlog | Maximum [Member]
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	3 years
Noncompete Agreements
Intangible assets subject to amortization:
Accumulated Amortization	$ 22.6	21.6
Net Carrying Amount	6.8	7.8
Total
Other Finite-Lived Intangible Assets, Gross	$ 29.4	$ 29.4
Noncompete Agreements | Minimum [Member]
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	1 year
Noncompete Agreements | Maximum [Member]
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	7 years