Quarterly report pursuant to Section 13 or 15(d)

Equity Method Investment in Affiliate - Additional Information (Detail)

v2.4.0.6
Equity Method Investment in Affiliate - Additional Information (Detail) (HA EnergySource [Member], Predecessor [Member], USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2013
Dec. 31, 2012
Schedule of Equity Method Investments [Line Items]    
Capital commitment, approved $ 1.8 $ 3.4
Capital commitment, paid 1.6  
Carrying value   0.5
Dividend Declared [Member]
   
Schedule of Equity Method Investments [Line Items]    
Reduction in equity, total   $ 3.9