Research Premium and Grant Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Research Premium and Grant Revenue
Research premium									$ 4,842	$ 6,232	$ 3,594
Government grants									369		67
Grants from WWFF and ZIT									108	250	106
Total	$ 1,122	$ 1,468	$ 1,051	$ 1,678	$ 2,307	$ 971	$ 1,785	$ 1,419	$ 5,319	$ 6,482	$ 3,767