Quarterly report pursuant to Section 13 or 15(d)

Business and Organization - Additional Information (Detail)

v3.7.0.1
Business and Organization - Additional Information (Detail)
3 Months Ended 12 Months Ended
Mar. 31, 2017
Segment
Dec. 31, 2016
Acquisition
Organization And Description Of Business [Line Items]    
Number of reportable segments | Segment 2  
Acquisitions 2016 [Member]    
Organization And Description Of Business [Line Items]    
Number of business acquisitions   5
Acquisitions 2016 [Member] | Electric Power Infrastructure Services Business [Member]    
Organization And Description Of Business [Line Items]    
Number of business acquisitions   4
Acquisitions 2016 [Member] | Electric Power Infrastructure Services Business [Member] | United States [Member]    
Organization And Description Of Business [Line Items]    
Number of business acquisitions   1
Acquisitions 2016 [Member] | Electric Power Infrastructure Services Business [Member] | Australia [Member]    
Organization And Description Of Business [Line Items]    
Number of business acquisitions   1
Acquisitions 2016 [Member] | Electric Power Infrastructure Services Business [Member] | Canada [Member]    
Organization And Description Of Business [Line Items]    
Number of business acquisitions   2
Acquisitions 2016 [Member] | Oil and Gas Infrastructure Services Business [Member] | United States [Member]    
Organization And Description Of Business [Line Items]    
Number of business acquisitions   1