Quarterly report pursuant to Section 13 or 15(d)

Acquisitions - Additional Information (Detail)

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Acquisitions - Additional Information (Detail) (USD $)
3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2014
Entity
Mar. 31, 2014
Entity
Jun. 30, 2014
Entity
Dec. 31, 2013
Entity
Business Acquisition [Line Items]        
Number of business acquisitions 1 5 6 6
Cash paid for acquisitions     $ 83,200,000 $ 341,100,000
Number of shares granted for acquired company     459,392 3,547,482
Common stock value     38,641,000 88,895,000
Fair value of accounts receivable acquired 31,200,000   31,200,000 83,900,000
Goodwill acquired     58,344,000  
Revenues contributed by acquisitions 47,600,000   84,600,000  
Income (loss) before income taxes contributed by acquisitions (2,200,000)   (2,300,000)  
Acquisition costs     4,300,000  
Electric Power Infrastructure Services Business [Member] | Canada [Member]
       
Business Acquisition [Line Items]        
Number of business acquisitions     4  
Electric Power Infrastructure Services Business [Member] | United States [Member]
       
Business Acquisition [Line Items]        
Number of business acquisitions     1  
Oil and Gas Infrastructure Services Business [Member] | United States [Member]
       
Business Acquisition [Line Items]        
Number of business acquisitions     1  
Acquisitions [Member]
       
Business Acquisition [Line Items]        
Goodwill expected to be deductible for income tax 11,300,000   11,300,000 213,600,000
Electric Power Division [Member]
       
Business Acquisition [Line Items]        
Goodwill acquired     50,788,000  
Electric Power Division [Member] | Acquisitions [Member]
       
Business Acquisition [Line Items]        
Goodwill acquired     50,800,000 112,500,000
Oil and Gas Infrastructure Division [Member]
       
Business Acquisition [Line Items]        
Goodwill acquired     7,556,000  
Oil and Gas Infrastructure Division [Member] | Acquisitions [Member]
       
Business Acquisition [Line Items]        
Goodwill acquired     $ 7,600,000 $ 143,300,000
Exchangeable Shares [Member] | Canadian Subsidiaries [Member]
       
Business Acquisition [Line Items]        
Number of shares granted for acquired company     899,858  
Series G Preferred Stock [Member]
       
Business Acquisition [Line Items]        
Number of shares granted for acquired company     1