Leases - Additional Information (Detail) $ in Thousands	1 Months Ended			3 Months Ended			6 Months Ended
	Oct. 31, 2018 ft²	Aug. 01, 2018 USD ($)	Mar. 31, 2017 ft² Lease	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)
Lessee Lease Description [Line Items]
Number of lease renewal option | Lease			1
Short term and variable lease cost				$ 100		$ 100	$ 200	$ 300
Rent expense				$ 200		300	1,300	1,400
Cash paid for measurement of lease obligations for operating cash flows from operating leases							$ 1,400	1,300
Weighted average remaining lease term				4 years 2 months 12 days			4 years 2 months 12 days
Weighted average discount rate				7.75%			7.75%
Write down of sublease receivable balance and previously capitalized commission charges							$ 1,383
2479 E. Bayshore Blvd, Palo Alto, California [Member] | Sublease Agreement [Member]
Lessee Lease Description [Line Items]
Operating facility lease area | ft²	4,240
Lease commencement date	2018-10
Lease expires date	Aug. 31, 2020
1020 Marsh Road, Menlo Park, California [Member]
Lessee Lease Description [Line Items]
Operating facility lease area | ft²			34,500
Lease commencement date			2017-08
Operating facility lease term			87 months
Lease agreement, one renewal option term			5 years
Operating facility lease term			87 months
1020 Marsh Road, Menlo Park, California [Member] | Sublease Agreement [Member] | EVA Automation, Inc [Member]
Lessee Lease Description [Line Items]
Operating facility lease term		72 months
Sublease commencement date		Oct. 01, 2018
Operating facility lease term		72 months
Abatement of base rent lease payment		$ 900
Operating lease abatement term		5 months
Write down of sublease receivable balance and previously capitalized commission charges					$ 1,400
Operating lease sublease income (loss)				$ 700		600	(100)	1,300
Cash received from sublease				$ 700		$ 500	$ 1,100	$ 800