Revenue - Reimbursement of R and D Costs (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Feb. 28, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Research and Development Reimbursement
Total reduction to R and D expense		$ 983	$ 3,208	$ 3,412	$ 6,453
Percentage of profit share	67.00%			65.00%
Operating expenses
Research and Development Reimbursement
Percentage of profit share					35.00%
Payable after the Company's R&D expenses had been reimbursed			1,500		$ 3,300
Mylan
Research and Development Reimbursement
Total reduction to R and D expense		53	2,598	$ 287	5,843
Percentage of profit share				35.00%
Janssen
Research and Development Reimbursement
Total reduction to R and D expense		$ 930	$ 610	$ 3,125	$ 610
Percentage of profit share	33.00%