Investment Fund (Details) - USD ($) $ in Thousands  | 
Mar. 31, 2016  | 
Dec. 31, 2015  | 
|---|---|---|
| Restricted Cash | ||
| Variable Interest Entity [Line Items] | ||
| Variable interest entity, carrying amount, assets | $ 1,556 | $ 5,419 | 
| Project Assets | ||
| Variable Interest Entity [Line Items] | ||
| Variable interest entity, carrying amount, assets | $ 33,096 | $ 32,657 | 
| X | ||||||||||
- Definition The carrying amount of the consolidated Variable Interest Entity's assets included in the reporting entity's statement of financial position. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
  | 
| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
  | 
| X | ||||||||||
- Details 
  | 
| X | ||||||||||
- Details 
  |