Stockholders' Equity - Additional Information (Details)			1 Months Ended	12 Months Ended
	May 01, 2019 USD ($)	Apr. 23, 2018 USD ($) $ / shares shares	Jan. 31, 2016 shares	Dec. 31, 2019 USD ($) Vote $ / shares shares	Dec. 31, 2018 $ / shares shares
Subsidiary Sale Of Stock [Line Items]
Common stock, authorized | shares				150,000,000	150,000,000
Common stock, par value | $ / shares				$ 0.0001	$ 0.0001
Number of votes entitled by each share of common stock holder | Vote				1
Common stock voting rights				Each share of common stock entitles the holder to one vote
Dividends, declared or paid				$ 0
Total reserved | shares				17,351,095	6,083,202
Common stock, issued | shares				27,893,337	27,772,600
Net proceeds from issuance of common stock				$ 24,000
ATM Facility
Subsidiary Sale Of Stock [Line Items]
Common stock, issued | shares				10,581
Net proceeds from issuance of common stock				$ 24,000
Initial Public Offering
Subsidiary Sale Of Stock [Line Items]
Net proceeds from issuance of common stock		$ 97,209,000
Issuance of common stock (in shares) | shares		7,200,000
Shares issued, price per share | $ / shares		$ 15.00
Gross proceeds from issuance of common stock		$ 108,000,000
JonesTrading Institutional Services LLC | ATM Facility | Maximum
Subsidiary Sale Of Stock [Line Items]
Gross proceeds from issuance of common stock	$ 30,000,000
Novartis Institutes for Biomedical Research, Inc. | Private Placement | Novartis Collaboration
Subsidiary Sale Of Stock [Line Items]
Net proceeds from issuance of common stock		$ 11,500,000
Issuance of common stock (in shares) | shares		766,666	766,666
Shares issued, price per share | $ / shares		$ 15.00