Acquisition of Icon Bioscience, Inc - Additional Information (Detail) - USD ($)		1 Months Ended	3 Months Ended	6 Months Ended
	Mar. 28, 2018	Apr. 30, 2019	Jun. 30, 2019	Jun. 30, 2019
Business Acquisition [Line Items]
Percentage of partnering income received to be paid quarterly as earn-out consideration	20.00%
Icon Bioscience Inc [Member]
Business Acquisition [Line Items]
Development milestone payment due following the first commercial sales of DEXYCU	$ 15,000,000
Maximum of potential sales milestone payments	$ 95,000,000
Quarterly percentage earn-out consideration due on product net sales	12.00%
Increased percentage earn-out on product net sales if net sales and partnering revenue exceed $200 million in a given year	16.00%
Contingent cash payments, description				These include but are not limited to (i) a one-time development milestone of $15.0 million payable in cash upon the first commercial sale of DEXYCU in the U.S., (ii) sales milestone payments totaling up to $95.0 million upon the achievement of certain sales thresholds and subject to certain Centers for Medicare & Medicaid Services (“CMS”) reimbursement conditions set forth in the Merger Agreement, (iii) quarterly earn-out payments equal to 12% on net sales of DEXYCU in a given year, which earn-out payments will increase to 16% of net sales of DEXYCU in such year beginning in the calendar quarter for such year to the extent aggregate annual DEXYCU consideration exceeds $200.0 million in such year, (iv) quarterly earn-out payments equal to 20% of partnering revenue received by the Company for DEXYCU outside of the U.S., and (v) single-digit percentage quarterly earn-out payments with respect to net sales and/or partnering income, if any, resulting from future clinical development, regulatory approval and commercialization of any other product candidates the Company acquired in the Icon Acquisition
Transaction costs	$ 2,000,000
Icon Bioscience Inc [Member] | Minimum [Member]
Business Acquisition [Line Items]
Threshold level of annual aggregate consideration above which the 16% royalty on net sales applies in any given year				$ 200,000,000
Icon Bioscience Inc [Member] | DEXYCU [Member]
Business Acquisition [Line Items]
Development milestone payment due following the first commercial sales of DEXYCU			$ 15,000,000	15,000,000
Estimated working capital adjustment at closing				127,000
Accrued development milestone consideration paid following the first commercial sale of DEXYCU	15,000,000	$ 15,000,000
Purchase price of acquisition	$ 32,000,000
Finite-lived intangible asset expected amortization life	13 years
Accrued sales-based royalty expense			$ 0	$ 99,000