Collaboration, License and Research Agreements - Reconciliation of Deferred Revenue Related to Lilly Agreement (Details) - Research Collaboration and License Agreement with Eli Lilly - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Balance	$ 18,940
Upfront payment		$ 20,000
Revenue recognized	(3,100)	(1,060)
Balance	$ 15,840	$ 18,940