Collaboration Arrangement (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2019
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue	$ 1,266	$ 1,032	$ 2,601	$ 2,281
Nippon Shinyaku Co., Ltd. (Shinyaku) | Collaborative arrangement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue	1,300	$ 1,000	2,600	$ 2,300
Deferred revenue	9,700		9,700
Nippon Shinyaku Co., Ltd. (Shinyaku) | Collaborative arrangement | Fixed consideration
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Performance obligation at inception of arrangement					$ 20,000
Nippon Shinyaku Co., Ltd. (Shinyaku) | Collaborative arrangement | Fixed consideration | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-04-01
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Timing of consideration to be received					2 years
Nippon Shinyaku Co., Ltd. (Shinyaku) | Collaborative arrangement | Achievement of regulatory milestones | Variable consideration
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Amount that can be earned upon achievement of milestone	66,000		66,000
Nippon Shinyaku Co., Ltd. (Shinyaku) | Collaborative arrangement | Achievement of net sales milestones | Variable consideration
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Amount that can be earned upon achievement of net sales milestone	$ 42,500		$ 42,500