Summary of Significant Accounting Policies - Schedule of Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Cash and cash equivalents	$ 17,732	$ 19,959	$ 19,721	$ 21,942
Restricted cash	2,916	2,957	3,195	3,251
Cash, cash equivalents, and restricted cash	$ 20,648	$ 22,916	$ 22,916	$ 25,193