Property, Plant and Equipment - Schedule of Property, Plant and Equipment (Detail) - USD ($) $ in Thousands |
Sep. 30, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Property, Plant and Equipment [Line Items] | ||
| Property, plant and equipment, gross | $ 3,722,828 | $ 3,703,781 |
| Less: accumulated depreciation | (540,774) | (409,161) |
| Property, plant and equipment, net | 3,182,054 | 3,294,620 |
| Operating wind farms [Member] | ||
| Property, Plant and Equipment [Line Items] | ||
| Property, plant and equipment, gross | 3,713,775 | 3,700,140 |
| Furniture, fixtures and equipment [Member] | ||
| Property, Plant and Equipment [Line Items] | ||
| Property, plant and equipment, gross | 8,912 | 3,500 |
| Land [Member] | ||
| Property, Plant and Equipment [Line Items] | ||
| Property, plant and equipment, gross | $ 141 | $ 141 |