Summary of Significant Accounting Policies - Schedule of Reconciliation of Cash, Cash Equivalents, and Restricted Cash (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 61,221	$ 75,567	$ 94,061
Restricted cash	32,864		877
Total cash, cash equivalents, and restricted cash shown in our consolidated statements of cash flows	$ 94,085	$ 75,567	$ 94,938	$ 106,005