Project Assets - Summary of Project Assets (Detail) - USD ($) $ in Thousands		Mar. 31, 2015	Dec. 31, 2014
Summary of Project Assets [Abstract]
Under development-Company as project owner		$ 113,948	$ 75,346
Under development-Company expected to be project owner upon the completion of construction	[1]	25,420	19,849
Total project assets		139,368	95,195
Current, net of impairment loss		107,354	73,930
Noncurrent		32,014	21,265
Total project assets		$ 139,368	$ 95,195

[1] All of the projects costs under this category were recorded as project assets, noncurrent.