Collaboration and Research Arrangements - Deferred revenue liabilities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Changes in deferred revenue liabilities:
Deferred revenue, Balance at Beginning of Period	$ 0
Deferred revenue, Additions	12,252
Deferred revenue, Deductions	2,050
Deferred revenue, Balance at End of Period	$ 10,202