Acquisitions (2013 Acquisitions - Other 2013 Acquisitions) (Narrative) (Details)	12 Months Ended
	Dec. 31, 2014
April 2013 Acquisition [Member]
Business Combinations [Line Items]
Business combinations, effective date	Apr. 01, 2013
Business combinations, description of acquired entity	a former subcontractor to its wireless business, which provides self-perform communications tower construction, installation, maintenance and other services in support of telecommunications infrastructure construction
August 2013 Acquisition [Member]
Business Combinations [Line Items]
Business combinations, effective date	Aug. 01, 2013
Business combinations, description of acquired entity	an electrical transmission services company, which focuses primarily on substation construction activities