Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Project Development Costs (Details)

v3.10.0.1
Summary of Significant Accounting Policies - Project Development Costs (Details) - USD ($)
$ in Thousands
Sep. 30, 2018
Dec. 31, 2017
Accounting Policies [Abstract]    
Capitalized project development costs, noncurrent $ 3,921 $ 1,524