Commercial Partnership (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
	Jun. 17, 2013	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	Oct. 31, 2014
License revenue		$ 1,277	$ 1,241	$ 1,259	$ 3,230	$ 1,267	$ 1,350	$ 1,453	$ 3,471	$ 7,007	$ 7,541	$ 6,420
Deferred revenue, short term		4,400				4,400				4,400	4,400
Deferred revenue, long term		19,617				24,017				19,617	24,017
Accrued expenses		8,577				12,150				8,577	12,150
Other long term liability		247				1,250				247	1,250
AbbVie, Inc. [Member]
Upfront Payment	$ 64,000
Contingent milestone payments	51,000									$ 0	0	0
License agreement, term										10 years
License revenue										$ 4,400	4,400	4,400
Deferred revenue	$ 44,000	24,000				28,400				24,000	28,400		$ 6,000
Deferred revenue, short term		4,400								4,400		$ 3,000	3,000
Deferred revenue, long term													$ 3,000
Royalties refunded											2,100
Royalties from resales refunded											2,900
Accrued expenses						2,200					2,200
Other long term liability		$ 2,900				$ 700				$ 2,900	$ 700