Acquisitions (2013 Acquisitions) (Narrative) (Details)	9 Months Ended
	Sep. 30, 2014
Big Country [Member]
Business Combinations [Line Items]
Business combinations, effective date	May 01, 2013
Business combinations, percentage of voting interests acquired	100.00%
Business combinations, name of acquired entity	Big Country Energy Services, Inc. and its affiliated operating companies (collectively, "Big Country").
Business combinations, description of acquired entity	Big Country, which is included in the Company's Oil and Gas segment, is a North American oil and gas pipeline and facility construction services company, headquartered in Calgary, Alberta, Canada.
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 that provides substation construction activities