Collaborative Arrangement (Details) - USD ($)	1 Months Ended	3 Months Ended		7 Months Ended	9 Months Ended
	Mar. 31, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Remaining amount to be billed in accordance with terms of agreement		$ 4,500,000		$ 4,500,000	$ 4,500,000
Collaboration revenue		630,000	$ 0		1,699,000	$ 0
Contract liability		$ 13,800,000		$ 13,800,000	13,800,000
Revenue recognized					$ 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	$ 20,000,000.0
Portion of fixed consideration received	$ 15,500,000			$ 15,500,000
Payment term				2 years
Variable Consideration | Achievement of Regulatory Milestones
Disaggregation of Revenue [Line Items]
Amount that can be earned upon achievement of milestone		$ 66,000,000.0		$ 66,000,000.0	$ 66,000,000.0
Variable Consideration | Achievement of Net Sales Milestones
Disaggregation of Revenue [Line Items]
Amount that can be earned upon achievement of net sales milestone		$ 42,500,000		$ 42,500,000	$ 42,500,000