Summary of Significant Accounting Policies - Schedule of Reconciliation of Cash, Cash Equivalents, and Restricted Cash (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 79,437	$ 105,662	$ 57,396
Restricted cash	0		17,082
Total cash, cash equivalents, and restricted cash shown in our consolidated statements of cash flows	$ 79,437	$ 105,662	$ 74,478	$ 102,518