License and Collaboration Agreements - Additional Information (Detail)				1 Months Ended		3 Months Ended			6 Months Ended
	Jan. 01, 2021	Dec. 12, 2018 USD ($)	Jul. 10, 2017 USD ($)	Nov. 30, 2018 USD ($)	Mar. 31, 2013 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) Country	Dec. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)
Collaborative Agreements And Contracts [Line Items]
Revenue						$ 7,210,000		$ 715,000	$ 9,222,000		$ 1,643,000
Accounts receivable						9,598,000			9,598,000	$ 627,000
Amended Alimera Agreement [Member]
Collaborative Agreements And Contracts [Line Items]
Royalty percentage earned from sales of product										2.00%
Calendar year net sales threshold for increase in royalty rate		$ 75,000,000
Contingently recoverable accumulated commercialization losses			$ 25,000,000						9,400,000
Partial cancellation of contingently recoverable accumulated commercialization losses in lieu of upfront license fee			$ 10,000,000
Royalty percentage offset for amounts earned above 2% to be applied against balance of accumulated commercialization losses		50.00%
Additional cancellation of contingently recoverable commercialization losses							$ 5,000,000
Accrued sales-based royalty income						500,000		196,000	1,016,000		379,000
Revenue						505,000		199,000	1,056,000		433,000
Amended Alimera Agreement [Member] | Scenario, Forecast [Member]
Collaborative Agreements And Contracts [Line Items]
Royalty percentage offset for amounts earned above 2% to be applied against balance of accumulated commercialization losses	20.00%
Amended Alimera Agreement [Member] | Minimum [Member]
Collaborative Agreements And Contracts [Line Items]
Royalty percentage earned from sales of product		6.00%
Amended Alimera Agreement [Member] | Maximum [Member]
Collaborative Agreements And Contracts [Line Items]
Royalty percentage earned from sales of product		8.00%
Bausch and Lomb [Member]
Collaborative Agreements And Contracts [Line Items]
Accounts receivable						0			$ 0	$ 253,000
OncoSil Medical UK Limited [Member]
Collaborative Agreements And Contracts [Line Items]
Royalty percentage earned from sales of product									8.00%
Revenue						0		0	$ 0		0
Percentage of non-royalty consideration received from sublicense									20.00%
Deferred revenue						0			$ 0
License agreement commencement date									2012-12
Receipt of upfront license fee					$ 100,000
Ocumension Therapeutics [Member]
Collaborative Agreements And Contracts [Line Items]
Revenue						0			$ 30,000
Deferred revenue						0			0
Receipt of upfront license fee				$ 1,750,000
Potential future payments that could be due based on achievement by Ocumension of certain prescribed development, regulatory and commercial sales-based milestones events									$ 10,000,000
ILUVIEN [Member] | Europe [Member]
Collaborative Agreements And Contracts [Line Items]
Number of countries in which lead licensed product received regulatory approval | Country									17
Royalty Income [Member]
Collaborative Agreements And Contracts [Line Items]
Revenue						500,000		497,000	$ 1,220,000		901,000
Royalty Income [Member] | Bausch and Lomb [Member]
Collaborative Agreements And Contracts [Line Items]
Revenue						0		301,000	204,000		522,000
Collaborative Research and Development [Member]
Collaborative Agreements And Contracts [Line Items]
Revenue						5,000		218,000	70,000		742,000
Collaborative Research and Development [Member] | OncoSil Medical UK Limited [Member]
Collaborative Agreements And Contracts [Line Items]
Revenue										$ 100,000
Collaborative Research and Development [Member] | Feasibility Study Agreement [Member]
Collaborative Agreements And Contracts [Line Items]
Revenue						0		$ 215,000	0		$ 685,000
Deferred revenue						$ 0			$ 0