Product Revenue Reserves and Allowances - Disaggregation of Revenue (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disclosure of Product Revenue Reserves and Allowances [Line Items]
Revenues	$ 2,509	$ 486	$ 11,732	$ 2,129
YUTIQ [Member]
Disclosure of Product Revenue Reserves and Allowances [Line Items]
Revenues	55		7,303
DEXYCU [Member]
Disclosure of Product Revenue Reserves and Allowances [Line Items]
Revenues	954		1,638
Product [Member]
Disclosure of Product Revenue Reserves and Allowances [Line Items]
Revenues	$ 1,009	$ 0	$ 8,941	$ 0