Collaboration Agreements - Additional Information (Details) - USD ($)		1 Months Ended	3 Months Ended		9 Months Ended
	May 24, 2019	Jun. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Recognized associated revenue					$ 20,000,000
Revenue from Contract with Customer, Product and Service [Extensible List]			us-gaap:LicenseMember	us-gaap:LicenseMember	us-gaap:LicenseMember	us-gaap:LicenseMember
Commercial License And Collaboration Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Non-refundable upfront payments received		$ 15,000,000
Additional upfront non-refundable amount payment payable		5,000,000	$ 5,000,000		$ 5,000,000
Upfront payment	$ 20,000,000
Upfront payment yet to be received	5,000,000
Recognized associated revenue	$ 20,000,000
Revenue from Contract with Customer, Product and Service [Extensible List]	us-gaap:LicenseMember
Commercial License And Collaboration Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Additional payments under agreement ability to receive		203,000,000
Commercial milestone payments		180,000,000
Development milestone payments		5,000,000
Commercial License And Collaboration Agreement | Minimum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Development milestone payments		$ 2,000,000