Balance Sheet Components - Summary 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 and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 90,908	$ 106,046	$ 133,829
Restricted cash included in other assets	300		175
Total cash, cash equivalents and restricted cash shown in the condensed consolidated statement of cash flows	$ 91,208	$ 106,346	$ 134,004	$ 100,536