Summary of Significant Accounting Policies - Additional information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Schedule Of Significant Accounting Policies [Line Items]
Accrued sales-based royalty expense	$ 517,000	$ 99,000
Icon Bioscience Inc [Member] | DEXYCU [Member]
Schedule Of Significant Accounting Policies [Line Items]
Accrued sales-based royalty expense	$ 400,000