Collaboration, License, Co-Promotion and Other Commercial Agreements - Co-Promotion Agreements (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended			12 Months Ended
	Aug. 09, 2019	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2019	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Collaboration, License and Co-Promotion Agreements
Revenue		$ 131,167		$ 65,686		$ 302,112	$ 215,947
Collaborative arrangements revenue
Collaboration, License and Co-Promotion Agreements
Revenue		130,524		54,194		273,998	188,487
Collaborative arrangement, co-promotion agreements
Collaboration, License and Co-Promotion Agreements
Revenue						2,600
Collaborative arrangement, promotion agreements
Collaboration, License and Co-Promotion Agreements
Revenue		1,400				1,400
Allergan | Collaborative arrangement, co-promotion agreements
Collaboration, License and Co-Promotion Agreements
Revenue		1,363	$ 1,300	$ 750		2,602	$ 2,250
Milestone payment to be received by company upon milestone achievement								$ 7,500
Collaborative arrangement compensated amount								$ 3,000
Allergan | Collaborative arrangement, promotion agreements
Collaboration, License and Co-Promotion Agreements
Milestone payment to be received by company upon milestone achievement					$ 4,200
Collaborative arrangement compensated amount					$ 4,100
Alnylam | Collaborative arrangement, co-promotion agreements
Collaboration, License and Co-Promotion Agreements
Revenue		722				722
Alnylam | Collaborative arrangement, promotion agreements
Collaboration, License and Co-Promotion Agreements
Deferred revenue		$ 1,300				1,300
Revenue						700
Total annual service fees due	$ 9,500
Term of agreement	3 years
Sales milestones | Allergan | Collaborative arrangement, co-promotion agreements
Collaboration, License and Co-Promotion Agreements
Milestone payment to be received by company upon milestone achievement						$ 3,000