Summary of Significant Accounting Policies - Schedule of Cash, Cash Equivalents and 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	$ 113,957	$ 72,280
Restricted cash	422	316
Total cash and cash equivalents and restricted cash	$ 114,379	$ 72,596	$ 186,366	$ 33,591