Leases - Additional Information (Details)	1 Months Ended			9 Months Ended
	May 31, 2020 USD ($)	May 31, 2019 USD ($)	Jun. 30, 2018 USD ($) ft² Investor shares	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)	May 13, 2019	Jul. 16, 2018
Lessee Lease Description [Line Items]
Lease agreement period								3 years
Renewal options		false
Number of investors | Investor			1
Operating lease payments		$ 0	$ 0
Repurchase option percentage			100.00%
Operating leases period			3 years
Operating lease payments paid for additional space		$ 63,000
Operating lease termination month and year	2021-07	2021-07
Operating lease liability	$ 172,000	$ 0		$ 523,000
Operating lease asset	$ 172,000			848,000		$ 625,000
Long-term operating lease liability				244,000
Future rent expense				760,000
Amortization expense of finance lease right-of-use asset				173,000	$ 53,000
Clinical Equipment
Lessee Lease Description [Line Items]
Remaining lease expense				$ 91,000
Remaining lease term				23 months
Minimum
Lessee Lease Description [Line Items]
Operating lease remaining term on a straight-line basis				10 months
Finance lease amortized period on equipment service				20 months
Maximum
Lessee Lease Description [Line Items]
Operating lease remaining term on a straight-line basis				34 months
Finance lease amortized period on equipment service				34 months
San Diego, California
Lessee Lease Description [Line Items]
Lease agreement period	3 years
Operating lease payments	$ 337,000
Operating lease asset	326,000
Long-term operating lease liability	317,000
Rent prepayment	9,000
San Diego, California | Other Assets
Lessee Lease Description [Line Items]
Security deposit paid	$ 29,000
Series B Redeemable Convertible Preferred Stock
Lessee Lease Description [Line Items]
Lease agreement period			3 years
Renewal options			false
Area under lease | ft²			3,185
Shares issued | shares			114,437
Convertible preferred stock, fair value			$ 1,100,000
Series B Redeemable Convertible Preferred Stock | IPO
Lessee Lease Description [Line Items]
Conversion of redeemable convertible preferred stock to common stock ratio		100.00%					100.00%