Related Party Transactions - Additional Information (Details) - USD ($)		3 Months Ended		9 Months Ended
	Jan. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Follow-on-offering
Related Party Transaction [Line Items]
Public offerings	9,602,500
Share price	$ 25.00
Follow-on-offering | Director
Related Party Transaction [Line Items]
Public offerings	20,000
Share price	$ 25.00
Two Thousand Fourteen Adimab Agreement
Related Party Transaction [Line Items]
Related party transaction expenses		$ 0		$ 0
Adimab
Related Party Transaction [Line Items]
Related party transaction expenses			$ 2,000,000		$ 2,800,000
Accrued liabilities due to related parties		0		0		$ 0
Adimab | Maximum
Related Party Transaction [Line Items]
Future milestone payments owed		$ 3,500,000		$ 3,500,000