Goodwill and Identified Intangible Assets Goodwill and Identified Intangible Assets (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	$ 3.1	$ 3.5
Schultz Mechanical Contractors, Inc. [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired through acquisition	2.3
Schultz Mechanical Contractors, Inc. [Member] | Trademarks [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired through acquisition	0.7
Schultz Mechanical Contractors, Inc. [Member] | Non-competes [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired through acquisition	$ 0.1