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Subsequent Events - Additional Information (Detail) (USD $)
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9 Months Ended | 0 Months Ended | 1 Months Ended | 1 Months Ended | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
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Sep. 30, 2014
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Apr. 29, 2014
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Dec. 31, 2013
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Sep. 30, 2014
Wind Loan Agreement [Member]
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Oct. 22, 2014
Subsequent Event [Member]
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Oct. 31, 2014
Subsequent Event [Member]
State
Company
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Oct. 31, 2014
Subsequent Event [Member]
Wind Project Investment [Member]
Project
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Oct. 31, 2014
Subsequent Event [Member]
Strong Upwind Holdings Llc, New Co [Member]
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Oct. 31, 2014
Subsequent Event [Member]
JP Morgan [Member]
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Oct. 31, 2014
Minimum [Member]
Subsequent Event [Member]
HA Wind [Member]
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Oct. 31, 2014
Maximum [Member]
Subsequent Event [Member]
HA Wind [Member]
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| 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 | |||||||||