Revenue from Contracts with Customers - Additional Information (Details) - USD ($)	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Revenue from Contracts with Customers [Line Items]
Bad debt expense	$ 0
Collaboration and License Agreement Revenues [Member]
Revenue from Contracts with Customers [Line Items]
Deferred revenue recognized	$ 0.0	$ 18,500,000
Collaboration and License Agreement Revenues [Member] | Takeda Collaboration and License Agreement [Member]
Revenue from Contracts with Customers [Line Items]
Milestone payment revenue		$ 37,500,000