Leases - Additional Information (Detail)	1 Months Ended			3 Months Ended
	Oct. 31, 2018 ft²	Aug. 01, 2018 USD ($)	Mar. 31, 2017 ft² Lease	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)
Lessee Lease Description [Line Items]
Number of lease renewal option | Lease			1
Operating lease costs				$ 700,000
Cash paid for measurement of lease obligations for operating cash flows from operating leases				$ 700,000
Weighted average remaining lease term				5 years 7 months 6 days
Weighted average discount rate				7.75%
1020 Marsh Road, Menlo Park, California [Member]
Lessee Lease Description [Line Items]
Operating facility lease area | ft²			34,500
Lease commencement date			August 2017
Operating facility lease term			86 months
Lease agreement, one renewal option term			5 years
1020 Marsh Road, Menlo Park, California [Member] | Sublease Agreement [Member] | EVA Automation, Inc [Member]
Lessee Lease Description [Line Items]
Lease commencement date		October 1, 2018
Operating facility lease term		72 months
Abatement of base rent lease payment		$ 900,000
Operating lease abatement term		5 months
Operating lease payments receivable				$ 700,000	$ 0
Cash received from sublease				$ 300,000
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	October 2018
Lease expires date	Aug. 31, 2020