Organization and Description of Business - Additional Information (Details) $ in Thousands	1 Months Ended		3 Months Ended			9 Months Ended
	Jul. 31, 2021 USD ($)	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($) shares	Sep. 30, 2020 shares	Jun. 30, 2020 shares	Sep. 30, 2021 USD ($) segment shares	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Organization and Description of Business [Line Item]
Accumulated deficit						$ 348,684		$ 260,723
Cash and cash equivalents						56,357		$ 28,122
Working capital						43,800
Aggregate offering price						200,000
Proceeds from issuance of common stock						60,336	$ 2,942
Proceeds from issuance of common stock, deducting underwriting discounts, commissions, and other offering costs			$ 60,200
Aggregate offering price, remaining						$ 132,600
Reportable segment | segment						1
Common Stock
Organization and Description of Business [Line Item]
Issuance of common stock in public offering, net (in shares) | shares			18,400,000	481,325	80,523	18,400,000
SFJ Pharmaceuticals X, Ltd.
Organization and Description of Business [Line Item]
Proceeds from partnership contribution						$ 10,900
Alfasigma S.p.A.
Organization and Description of Business [Line Item]
Upfront payment from sublicense agreement	$ 20,000	$ 20,000
Equity Distribution Agreement with Citigroup Global Markets Inc. and William Blair & Company, L.L.C.
Organization and Description of Business [Line Item]
Aggregate offering price						60,000
Proceeds from issuance of common stock						2,900
Aggregate offering price, remaining						$ 57,000
Equity Distribution Agreement with Citigroup Global Markets Inc. and William Blair & Company, L.L.C. | Common Stock
Organization and Description of Business [Line Item]
Issuance of common stock in public offering, net (in shares) | shares						561,848