Commitments and Contingencies - Additional Information (Detail)	1 Months Ended			3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Nov. 30, 2019 USD ($)	Jul. 31, 2019 USD ($) ft²	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)
Commitments and Contingencies [Line Items]
Sublease income					$ 43,000		$ 173,000
Redwood City, California [Member]
Commitments and Contingencies [Line Items]
Area of operating lease | ft²			6,368
Operating lease, description						the Company executed a non-cancellable lease agreement for 6,368 square feet of new space in Redwood City, California, which began in September 2019 and expires in May 2021
Operating lease beginning date			2019-09
Operating lease, expiration			2021-05
Payment to acquire office furniture under operating lease			$ 1
Future minimum commitment under non-cancelable operating lease	$ 30,000	$ 29,000
Capnia Inc Joint Venture [Member] | Redwood City, California [Member]
Commitments and Contingencies [Line Items]
Sublease income				$ 16,000		$ 65,000