Commitments and Contingencies - Summary of Commitments and Contingencies (Detail)	Mar. 31, 2019 USD ($)
Commitment And Contingencies [Line Items]
Total	$ 9,222,000
2019	7,543,000
2020	335,000
2021	345,000
2022	355,000
2023	364,000
Thereafter	280,000
Clinical research and trial obligations [Member]
Commitment And Contingencies [Line Items]
Total	6,162,000
2019	6,162,000
2021	0
2022	0
2023	0
Thereafter	0
Biologics License Application (BLA) consulting services [Member]
Commitment And Contingencies [Line Items]
Total	1,135,000
2019	1,135,000
2021	0
2022	0
2023	0
Thereafter	0
Facility lease [Member]
Commitment And Contingencies [Line Items]
Total	1,925,000
2019	246,000
2020	335,000
2021	345,000
2022	355,000
2023	364,000
Thereafter	$ 280,000