Quarterly report pursuant to Section 13 or 15(d)

Subsequent Events - Additional Information (Detail)

v2.4.0.8
Subsequent Events - Additional Information (Detail) (USD $)
9 Months Ended 0 Months Ended 1 Months Ended 1 Months Ended
Sep. 30, 2014
Apr. 29, 2014
Dec. 31, 2013
Sep. 30, 2014
Wind Loan Agreement [Member]
Oct. 22, 2014
Subsequent Event [Member]
Oct. 31, 2014
Subsequent Event [Member]
State
Company
Oct. 31, 2014
Subsequent Event [Member]
Wind Project Investment [Member]
Project
Oct. 31, 2014
Subsequent Event [Member]
Strong Upwind Holdings Llc, New Co [Member]
Oct. 31, 2014
Subsequent Event [Member]
JP Morgan [Member]
Oct. 31, 2014
Minimum [Member]
Subsequent Event [Member]
HA Wind [Member]
Oct. 31, 2014
Maximum [Member]
Subsequent Event [Member]
HA Wind [Member]
Subsequent Event [Line Items]                      
Project investment amount             $ 144,000,000        
Number of operating projects             10        
Non-recourse debt 93,620,000   100,081,000     115,000,000          
Ownership percentage 100.00%             50.00%      
Ownership percentage                 50.00%    
Number of limited liability companies           4          
Number of States           5          
Ownership interest based on voting percentage                   4.00% 17.50%
Fixed interest rate of loan         5.74%            
Percentage of minimum principal payment amount           Minimum principal payment amount equal to one-half percent (0.5%) of the principal amount of the loans plus additional principal payments based on available cash flow and a target debt balance.          
Maturity date of loan Sep. 30, 2021                    
Repayment of remaining debt balance in 2021 20,200,000                    
Debt instrument floating rate 4.25%                    
Default interest rate on debt in an event of default       7.74%              
First follow-on public offering, shares   5,750,000       4,600,000          
Share issued pursuant to underwriter   750,000       600,000          
First follow-on public offering, price per share   $ 13.00       $ 13.60          
Net proceeds from first follow-on from public offering   $ 70,400,000       $ 58,900,000