Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Summary of Estimated Fair Value of Company's Investments in Marketable Securities, Accounted for as Available-for-Sale Securities (Details)

v3.8.0.1
Summary of Significant Accounting Policies - Summary of Estimated Fair Value of Company's Investments in Marketable Securities, Accounted for as Available-for-Sale Securities (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Available For Sale Securities [Abstract]    
Due within one year $ 30,991  
Total $ 30,991 $ 21,033