Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Restricted Cash (Details)

v3.10.0.1
Summary of Significant Accounting Policies - Restricted Cash (Details) - USD ($)
$ in Thousands
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Accounting Policies [Abstract]      
Restricted cash, noncurrent $ 19,637 $ 20,092 $ 19,920