Organization and Summary of Significant Accounting Policies - Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue, current portion	$ 47,564		$ 28,345
Deferred revenue, noncurrent portion	108,273		29,244
Accumulated deficit	(562,696)		$ (495,479)
Topic 606 [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue, current portion		$ 29,626
Deferred revenue, noncurrent portion		26,846
Accumulated deficit		(494,362)
Adjustments [Member] | Topic 606 [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue, current portion	15,553	1,281
Deferred revenue, noncurrent portion	(879)	(2,398)
Accumulated deficit	(14,674)	1,117
Balances without adoption of Topic 606 [Member] | Topic 606 [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue, current portion	63,117	28,345
Deferred revenue, noncurrent portion	107,394	29,244
Accumulated deficit	$ (577,370)	$ (495,479)