Related Party Transactions - Additional Information (Details) - Royalty Transfer Agreement $ in Thousands		6 Months Ended
	Jun. 11, 2018 USD ($) Investor	Jun. 30, 2020
Related Party Transaction [Line Items]
Royalty owed to charitable foundation	$ 0
Product
Related Party Transaction [Line Items]
Net product sales	$ 0
MPM Oncology Charitable Foundation, Inc. and UBS Optimus Foundation
Related Party Transaction [Line Items]
Number of investors | Investor	2
Obligation to pay royalties		Royalty equal to 1% percent of its net product sales each year within 120 days following each year end.
Percentage of royalty required to pay	1.00%