Commitments and Contingencies - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2019 USD ($) Milestone	Oct. 31, 2014 USD ($)
Intellectual Property [Member]
Other Commitments [Line Items]
Milestone fees	$ 2,800,000
Maximum percentage of royalties on sales	5.00%
Intellectual Property [Member] | Regulatory [Member]
Other Commitments [Line Items]
Number of milestones achieved | Milestone	1
Intellectual Property [Member] | Development [Member]
Other Commitments [Line Items]
Number of milestones achieved | Milestone	6
Royalty Agreements [Member]
Other Commitments [Line Items]
Milestone fees	$ 500,000
Maximum percentage of royalties on sales	1.00%
Royalty period	10 years
Data License Agreement [Member]
Other Commitments [Line Items]
Description of royalties payable	The Company is obligated to pay Ipsen low single-digit royalties on annual net sales of OTO-313 by the Company or its affiliates or sublicensees
Maximum cumulative royalties paid under license agreement		$ 10,000,000