Summary of Significant Accounting Policies - Schedule of Reconciliation of Cash, Cash Equivalents, and Restricted Cash (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 107,057	$ 69,654	$ 33,521
Restricted cash		32,864	34,278
Total cash, cash equivalents, and restricted cash shown in our consolidated statements of cash flows	$ 107,057	$ 102,518	$ 67,799	$ 75,567