Annual report pursuant to Section 13 and 15(d)

Business and Organization - Additional Information (Detail)

v2.4.0.6
Business and Organization - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2012
Entity
Dec. 31, 2011
Entity
Organization And Description Of Business [Line Items]    
Fiber Optic Licensing Terms, Minimum in years 5 years  
Fiber Optic Licensing Terms, Maximum in years 25 years  
Number of business acquisitions completed 4 5
Proceeds from sale of subsidiary $ 265  
Electric Power Division [Member] | Canada [Member]
    
Organization And Description Of Business [Line Items]    
Number of business acquisitions completed 1 3
Electric Power Division [Member] | United States [Member]
    
Organization And Description Of Business [Line Items]    
Number of business acquisitions completed 2 1
Natural Gas and Pipeline Division [Member] | United States [Member]
    
Organization And Description Of Business [Line Items]    
Number of business acquisitions completed 1  
Natural Gas and Pipeline Division [Member] | Australia [Member]
    
Organization And Description Of Business [Line Items]    
Number of business acquisitions completed   1