Commitments and Contingencies - Additional Information (Detail) $ in Millions	1 Months Ended				3 Months Ended
	Apr. 30, 2019	Jun. 30, 2018	Apr. 30, 2018 ft²	Jun. 30, 2014 ft²	Mar. 31, 2019 USD ($) ft²	Mar. 31, 2018 USD ($)
Operating Leased Assets [Line Items]
Weighted-average remaining lease term					6 years 4 months 24 days
Weighted-average discount rate					7.70%
Rent expense | $						$ 0.2
Purchase commitments | $					$ 7.3
Lease Agreement | Oakwood Village, Ohio
Operating Leased Assets [Line Items]
Area of land | ft²					19,800
Lease agreement, expiration date					Oct. 31, 2019
Option to extend, description operating lease					extend the term of the lease agreement through October 2021
Lease Agreement | Mountain View, California
Operating Leased Assets [Line Items]
Area of land | ft²			24,600	25,500
Lease agreement, expiration date		Jul. 31, 2025	Dec. 31, 2025	Nov. 30, 2019
Option to extend, description operating lease		extend the term of the lease agreement through July 2025
Option to extend, existence operating Lease		true
Lease commencement date			2018-12
Lease Agreement | Mountain View, California | Maximum
Operating Leased Assets [Line Items]
Lease agreement, renewal term			5 years
Lease Agreement | Subsequent Event | Oakwood Village, Ohio
Operating Leased Assets [Line Items]
Option to extend, existence operating Lease	true
Lease agreement, option to extend expiration date	Oct. 31, 2021