Goodwill and Identifiable Assets (Acquired Intangible Assets) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019		Dec. 31, 2018
Intangible assets subject to amortization:
Gross Carrying Amount	$ 500.9		$ 483.5
Accumulated Amortization	282.9		257.0
Net Carrying Amount	218.0		226.5
Intangible assets not subject to amortization:
Trademarks, Carrying Amount	258.9	[1]	262.2
Write-off of Intangible Assets (Excluding Goodwill)	3.3
Intangible Assets, Gross (Excluding Goodwill)	759.8		745.7
Intangible Assets, Net (Excluding Goodwill)	476.9		488.7
Customer and Contractual Relationships
Intangible assets subject to amortization:
Gross Carrying Amount	362.4		346.9
Accumulated Amortization	162.4		145.4
Net Carrying Amount	$ 200.0		201.5
Customer and Contractual Relationships | Minimum [Member]
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	2 months
Customer and Contractual Relationships | Maximum [Member]
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	12 years 9 months
Contractor Relations
Intangible assets subject to amortization:
Gross Carrying Amount	$ 71.0		71.1
Accumulated Amortization	70.4		67.1
Net Carrying Amount	$ 0.6		4.0
Contractor Relations | Minimum [Member]
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	2 years
Contractor Relations | Maximum [Member]
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	5 years
Backlog
Intangible assets subject to amortization:
Gross Carrying Amount	$ 25.0		23.1
Accumulated Amortization	20.7		17.7
Net Carrying Amount	$ 4.3		5.4
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	2 years 9 months
Noncompete Agreements
Intangible assets subject to amortization:
Gross Carrying Amount	$ 23.6		22.1
Accumulated Amortization	11.9		9.9
Net Carrying Amount	$ 11.7		12.2
Noncompete Agreements | Minimum [Member]
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	2 years
Noncompete Agreements | Maximum [Member]
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	7 years
In-use software
Intangible assets subject to amortization:
Gross Carrying Amount	$ 18.9		18.9
Accumulated Amortization	17.5		16.0
Net Carrying Amount	$ 1.4		2.9
In-use software | Minimum [Member]
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	6 years
Favorable Contracts
Intangible assets subject to amortization:
Gross Carrying Amount	$ 0.0		1.4
Accumulated Amortization	0.0		0.9
Net Carrying Amount	$ 0.0		$ 0.5
Favorable Contracts | Minimum [Member]
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	5 years

[1] Certain foreign trademarks totaling $3.3 million were written off during the second quarter of 2019.