Collaborative Arrangement (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		4 Months Ended	6 Months Ended
	Mar. 31, 2019	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Remaining amount to be billed in accordance with terms of agreement		$ 4,500		$ 4,500	$ 4,500
Collaboration revenue		$ 1,069	$ 0		$ 1,069	$ 0
Minimum
Disaggregation of Revenue [Line Items]
Timing of consideration to be received		3 years		3 years	3 years
Maximum
Disaggregation of Revenue [Line Items]
Timing of consideration to be received		4 years		4 years	4 years
Fixed Consideration
Disaggregation of Revenue [Line Items]
Performance obligation at inception of arrangement	$ 20,000	$ 20,000		$ 20,000	$ 20,000
Portion of fixed consideration received				15,500
Payment term	2 years
Contract liability		$ 14,400		$ 14,400	$ 14,400
Variable Consideration | Achievement of Regulatory Milestones
Disaggregation of Revenue [Line Items]
Amount that can be earned upon achievement of milestone	$ 66,000
Variable Consideration | Achievement of Net Sales Milestones
Disaggregation of Revenue [Line Items]
Amount that can be earned upon achievement of net sales milestone	$ 42,500