Stock-Based Compensation - Additional Information (Detail)	Apr. 27, 2017 shares
2015 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation, additional shares authorized (in shares)	1,200,000
Share based compensation, shares authorized (in shares)	5,755,277
2017 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation, shares authorized (in shares)	250,000
Employee stock purchase plan offering period	6 months
Percentage of discount on closing price	15.00%