Collaboration and Other Agreements, Green Cross (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2010	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2014	Dec. 31, 2015
Collaboration And Other Agreements [Line Items]
Deferred revenue included in current liabilities		$ 4,578		$ 4,578			$ 5,866
Deferred revenue included in long-term liabilities		10,740		$ 10,740			12,631
Green Cross [Member]
Collaboration And Other Agreements [Line Items]
Collaboration or other agreement date				June 2010
Non-refundable upfront payment	$ 1,000
Term of the agreement				June 2020
Adjustment to revenue from contract material modification						$ 1,300
Recognized revenue under agreement		100	$ 100	$ 200	$ 200
Deferred revenue		1,800		1,800			2,000
Deferred revenue included in current liabilities		400		400			400
Deferred revenue included in long-term liabilities		1,400		1,400			$ 1,600
Green Cross [Member] | Maximum [Member]
Collaboration And Other Agreements [Line Items]
Aggregate potential future cost reimbursement		5,500		5,500
Clinical and commercial milestone payments		$ 2,500		$ 2,500