Acquisitions (Schedule of Finite-Lived Intangible Assets Acquired, Business Acquisitions - WesTower) (Details) - Oct. 01, 2014 - WesTower [Member] - USD ($) $ in Millions	Total
Business Combinations [Line Items]
Finite-lived intangible assets, fair value (in dollars)	$ 42.6
Finite-lived intangible assets, weighted average useful life (in years)	16 years
Backlog [Member]
Business Combinations [Line Items]
Finite-lived intangible assets, fair value (in dollars)	$ 4.7
Finite-lived intangible assets, weighted average useful life (in years)	5 years
Trade Name [Member]
Business Combinations [Line Items]
Finite-lived intangible assets, fair value (in dollars)	$ 1.1
Finite-lived intangible assets, weighted average useful life (in years)	4 years
Non-Compete Agreements [Member]
Business Combinations [Line Items]
Finite-lived intangible assets, fair value (in dollars)	$ 0.3
Finite-lived intangible assets, weighted average useful life (in years)	4 years
Customer Relationships [Member]
Business Combinations [Line Items]
Finite-lived intangible assets, fair value (in dollars)	$ 36.5
Finite-lived intangible assets, weighted average useful life (in years)	18 years