Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies (Details)

v3.8.0.1
Summary of Significant Accounting Policies (Details) - USD ($)
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Summary of Significant Accounting Policies [Abstract]      
Restricted cash $ 7,558,000 $ 7,557,000 $ 7,557,000