Common Stock, Redeemable Common Stock and Convertible Preferred Stock (converted to Common Stock) - Additional Information (Details) - USD ($)			1 Months Ended	12 Months Ended
	Nov. 26, 2019	Apr. 12, 2019	Aug. 31, 2015	Dec. 31, 2019	Nov. 29, 2019	Apr. 16, 2019	Dec. 31, 2018	Aug. 31, 2014
Class of Stock [Line Items]
Common stock, authorized (in shares)				33,333,333			11,070,776
Common stock par value (in dollars per share)				$ 0.001			$ 0.001
Cash dividends				$ 0
Stock issued (in shares)	3,666,667	5,670,000
Sale price (in dollars per share)	$ 12.00	$ 11.00
Warrant expiration period	30 days	5 years
Proceeds from common stock issuance	$ 65,000,000.0	$ 85,800,000
Fair value of additional common stock issued			$ 734,000
Preferred stock, authorized (in shares)							49,413,523
Preferred stock outstanding				$ 0
Series Seed Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, authorized (in shares)				10,000,000			59,413,523
Preferred stock par value (in dollars per share)				$ 0.001			$ 0.001
Genzyme Agreement
Class of Stock [Line Items]
Stock issued (in shares)			107,371
Sale price (in dollars per share)								$ 0.01
Shares issued for additional consideration (in shares)			107,371
Common stock purchase price (in dollars per share)			$ 0.001
Pre Funded Warrant
Class of Stock [Line Items]
Common stock par value (in dollars per share)						$ 0.001
Number of warrants issued (in shares)	1,750,000	2,130,000
Convertible preferred stock exercise price (in dollars per share)	$ 11.999	$ 10.999			$ 11.999	10.999
Class A Warrant
Class of Stock [Line Items]
Number of warrants issued (in shares)		3,900,000
Convertible preferred stock exercise price (in dollars per share)		$ 13.20				$ 13.20
Class B Warrants
Class of Stock [Line Items]
Number of warrants issued (in shares)	5,416,667
Convertible preferred stock exercise price (in dollars per share)	$ 15.00				$ 15.00