Stock-Based Compensation - Summary of Stock Option Activity for 2015 Private Dare Plan and 2014 Plan and Related Information (Detail) (Parenthetical) - shares |
Jun. 30, 2018 |
Dec. 31, 2017 |
Jul. 19, 2017 |
---|---|---|---|
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
Stock options outstanding | 547,571 | 539,896 | |
Private Dare [Member] | Stock Options [Member] | 2015 Stock Incentive Plan [Member] | |||
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
Stock options outstanding | 10,149 | 50,000 |