Agreements - Debiopharm (Details) - USD ($)		1 Months Ended		3 Months Ended			6 Months Ended
	May 24, 2017	Jan. 31, 2018	Dec. 31, 2017	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Collaborative Agreements disclosures
License and milestone fees				$ 1,321,000		$ 31,080,000	$ 12,861,000	$ 49,810,000
Research and development support				$ 388,000		$ 902,000	771,000	$ 2,380,000
Debiopharm
Collaborative Agreements disclosures
Payments received under collaboration agreement	$ 25,000,000
Potential milestone payment	5,000,000		$ 4,500,000		$ 5,000,000		$ 0
Fair value of consideration for services provided	30,000,000
License and milestone fees	29,700,000	$ 500,000			$ 29,500,000
Research and development support	300,000
Debiopharm | Phase 3 Clinical Trial
Collaborative Agreements disclosures
Potential milestone payment	$ 25,000,000