Organization, Basis of Presentation and Summary of Significant Accounting Policies - Condensed Consolidated Statement of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Organization And Summary Of Significant Accounting Policies [Line Items]
Net loss	$ (20,187)	$ (16,632)
Changes in deferred revenue	2,701	$ (870)
Adjustments [Member] | Topic 606 [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Net loss	1,746
Changes in deferred revenue	(1,746)
Balances without adoption of Topic 606 [Member] | Topic 606 [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Net loss	(21,933)
Changes in deferred revenue	$ 4,447