Stock Benefit Plans and Stock-Based Compensation - Summary Common Stock Reserved for Future Issuance (Detail) shares in Thousands	Dec. 31, 2019 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	43,664
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	4,215
Unvested restricted stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	6,727
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	117
Series A Convertible Preferred Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	67
Warrants Outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	26,557
Authorized for Future Grant Under the Distributor and Development Services Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	3,908
Authorized for Future Grant Under the Management Objective Strategic Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	445
Authorized for Future Grant Under the Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	1,628