Commitments - License agreements (Details) $ in Thousands	9 Months Ended
Sep. 30, 2018 USD ($) item	Sep. 30, 2017 USD ($)
License agreements
Commitments
Number of biotechnology companies where Company has licensed intellectual property \| item	2
Milestone payments	$ 0	$ 2,250
Manufacturing services agreement
Commitments
Amount of commitment	$ 5,700

Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

No definition available.

Name:	us-gaap_OtherCommitment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant