Accounts Payable and Other Accrued Liabilities - Components of Accounts Payable and Other Accrued Liabilities (Detail) - USD ($) $ in Thousands |
Sep. 30, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Payables and Accruals [Abstract] | ||
| Accounts payable | $ 1,848 | $ 625 |
| Other accrued liabilities | 9,420 | 9,583 |
| Operating wind farm upgrade liability | 1,012 | 4,909 |
| Turbine operations and maintenance payable | 836 | 985 |
| Purchase agreement obligations | 0 | 5,749 |
| Land lease rent payable | 1,396 | 2,513 |
| Spare-parts inventory payables | 550 | 1,181 |
| Payroll liabilities | 6,268 | 5,345 |
| Property tax payable | 10,391 | 11,145 |
| Sales tax payable | 1,147 | 741 |
| Accounts payable and other accrued liabilities | $ 32,868 | $ 42,776 |