Collaborative Arrangements - Reimbursement of R and D Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Research and Development Reimbursement
Total reduction to R and D expense	$ 1,850	$ 7,126
Mylan
Research and Development Reimbursement
Total reduction to R and D expense	$ 1,850	7,089
Other
Research and Development Reimbursement
Total reduction to R and D expense		$ 37