Quarterly report pursuant to Section 13 or 15(d)

Business and Organization - Additional Information (Detail)

v2.4.0.8
Business and Organization - Additional Information (Detail) (USD $)
In Millions, except Share data, unless otherwise specified
3 Months Ended 6 Months Ended 12 Months Ended 1 Months Ended 6 Months Ended
Jun. 30, 2013
Jun. 30, 2012
Jun. 30, 2013
Jun. 30, 2012
Dec. 31, 2012
Jul. 31, 2013
Subsequent Event [Member]
Entity
Jun. 30, 2012
Electric Power Division [Member]
United States [Member]
Entity
Jun. 30, 2012
Electric Power Division [Member]
Canada [Member]
Entity
Jun. 30, 2012
Natural Gas and Pipeline Division [Member]
United States [Member]
Entity
Organization And Description Of Business [Line Items]                  
Fiber Optic Licensing Terms, Minimum in years 5 years 5 years 5 years 5 years 5 years        
Fiber Optic Licensing Terms, Maximum in years 25 years 25 years 25 years 25 years 25 years        
Number of business acquisitions           2 2 1 1
Cash paid for acquisition       $ 57.5   $ 118.0      
Number of shares issued for acquisition of company       1,927,113   763,272      
Common stock value       37.3   18.7      
Payment of cash to repay acquiree debt       11.0          
Proceeds from sale of subsidiary         $ 265.0