License and Collaboration Agreements - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended
	Nov. 30, 2019	Mar. 31, 2020	Dec. 31, 2019
Research And Development Arrangement Contract To Perform For Others [Line Items]
Payments on license agreement milestone in acquired in process research and development expenses		$ 10,000,000.0
Agenus Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront fee	$ 10,000,000.0
Maximum amount payable upon achieving certain clinical development and regulatory milestones	115,000,000.0
Maximum amount payable upon achieving certain commercial milestones	$ 85,000,000.0
License agreement milestone in acquired in-process research and development expenses			$ 10,000,000.0
Agenus Agreement | After First Commercial Sale of Licensed Product
Research And Development Arrangement Contract To Perform For Others [Line Items]
License agreement expiration term	15 years
Maximum | Agenus Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Royalty ranging on net sales of licensed products	20.00%
Minimum | Agenus Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Royalty ranging on net sales of licensed products	14.00%
Allergan | License Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Milestone payments received for licensing agreement		25,000,000.0
Allergan | License Agreement | Maximum
Research And Development Arrangement Contract To Perform For Others [Line Items]
License agreement additional milestone payments eligible to receive		$ 200,000,000.0