Summary of Significant Accounting Policies - Additional information (Detail) - DEXYCU [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Schedule Of Significant Accounting Policies [Line Items]
Accrued revenue-based royalty expense	$ 99,000	$ 0	$ 616,000	$ 99,000
Icon Bioscience Inc [Member]
Schedule Of Significant Accounting Policies [Line Items]
Accrued revenue-based royalty expense	$ 0		$ 400,000