Collaboration Agreements - Additional Information (Details)	1 Months Ended	3 Months Ended		9 Months Ended
	Nov. 30, 2017 TargetAntigen	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue		$ 50,000	$ 625,000	$ 900,000	$ 625,000
Surface Oncology, Inc.
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of target antigens against which antibodies are to be identified and selected | TargetAntigen	2
Revenue		50,000		900,000
Surface Oncology, Inc. | Exclusive Product License
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue		$ 50,000	$ 50,000	850,000	$ 50,000
Annual maintenance fee				$ 50,000
Surface Oncology, Inc. | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Term of research program	9 months
Surface Oncology, Inc. | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Term of research program	12 months