Revenue - Revenue from Collaborative Arrangements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Collaboration revenue recognized in the period from:
Revenue from collaborative arrangements	$ 26,464	$ 31,245	$ 130
Janssen
Collaboration revenue recognized in the period from:
Revenue from collaborative arrangements	26,426	31,096	31,053
Alfasigma
Collaboration revenue recognized in the period from:
Revenue from collaborative arrangements	14	125	10,678
Other
Collaboration revenue recognized in the period from:
Revenue from collaborative arrangements	24	29	60
Collaborative revenue
Collaboration revenue recognized in the period from:
Revenue from collaborative arrangements	$ 26,464	$ 31,250	$ 41,791