Business and Organization - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2012 Entity	Dec. 31, 2014 Segment Entity	Dec. 31, 2013 Entity	Dec. 31, 2012 Entity
Organization And Description Of Business [Line Items]
Number of reportable segments		3
Fiber Optic Licensing Terms, Minimum in years		5 years	5 years
Fiber Optic Licensing Terms, Maximum in years		25 years	25 years
Number of business acquisitions	4	9	6	4
Proceeds from sale of subsidiary				$ 265.0
Electric Power Infrastructure Services Business [Member] | Canada [Member]
Organization And Description Of Business [Line Items]
Number of business acquisitions	1	4
Electric Power Infrastructure Services Business [Member] | Australia [Member]
Organization And Description Of Business [Line Items]
Number of business acquisitions		1
Electric Power Infrastructure Services Business [Member] | United States [Member]
Organization And Description Of Business [Line Items]
Number of business acquisitions	2	1
Electric Power Infrastructure Services Business [Member] | Us Canada Australia [Member]
Organization And Description Of Business [Line Items]
Number of business acquisitions			3
Oil and Gas Infrastructure Services Business [Member] | Canada [Member]
Organization And Description Of Business [Line Items]
Number of business acquisitions		2
Oil and Gas Infrastructure Services Business [Member] | United States [Member]
Organization And Description Of Business [Line Items]
Number of business acquisitions	1	1
Oil and Gas Infrastructure Services Business [Member] | Us Canada Australia [Member]
Organization And Description Of Business [Line Items]
Number of business acquisitions			3