Development, Commercialization and Supply Agreement - Additional Information (Detail)	1 Months Ended				3 Months Ended		9 Months Ended		12 Months Ended	16 Months Ended	25 Months Ended	47 Months Ended	56 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Mar. 31, 2016 USD ($)	Feb. 28, 2015 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) Item	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2017 USD ($)
License And Collaboration Agreements [Line Items]
Revenue recognized related to upfront and milestone payments							$ 1,131,000	$ 598,000
Licenses revenue					$ 112,408,000	$ 55,323,000	286,478,000	151,884,000
Deferred revenue	$ 20,956,000				19,579,000	20,956,000	19,579,000	20,956,000	$ 20,710,000	$ 20,710,000	$ 19,579,000	$ 20,710,000	$ 19,579,000	$ 19,054,000
Licensing Revenue
License And Collaboration Agreements [Line Items]
Licenses revenue					158,000	$ 350,000	$ 1,131,000	598,000
Mochida | In-licenses | Research and Development Expense
License And Collaboration Agreements [Line Items]
Upfront payment									2,700,000
Eddingpharm | Out-licenses
License And Collaboration Agreements [Line Items]
Non-refundable up-front received				$ 15,000,000.0
Number of indications of the regulatory milestone events relating to the submission and approval | Item							3
Amounts to be received upon achievement of the regulatory milestone events							$ 33,000,000.0
Sales-based milestone event payment							120,000,000.0
Revenue recognized related to upfront and milestone payments							200,000	100,000
Deferred revenue					13,000,000.0		13,000,000.0		13,200,000	13,200,000	13,000,000.0	13,200,000	13,000,000.0
Eddingpharm | Out-licenses | Licensing Revenue
License And Collaboration Agreements [Line Items]
Licenses revenue												2,800,000	3,000,000.0
Eddingpharm | Out-licenses | Maximum
License And Collaboration Agreements [Line Items]
Additional upfront payment eligible to receive based on development, regulatory and sales Milestone							153,000,000.0
Amounts to be received upon achievement of the regulatory milestone events							15,000,000.0
Sales-based milestone event payment							50,000,000.0
Eddingpharm | Out-licenses | Minimum
License And Collaboration Agreements [Line Items]
Amounts to be received upon achievement of the regulatory milestone events							2,000,000.0
Sales-based milestone event payment							5,000,000.0
Eddingpharm | Out-licenses | Clinical Trial Application
License And Collaboration Agreements [Line Items]
Non-refundable milestone payment			$ 1,000,000.0
Biologix FZCo | Out-licenses
License And Collaboration Agreements [Line Items]
Revenue recognition period of non-refundable up-front payment			10 years
HLS | Out-licenses
License And Collaboration Agreements [Line Items]
Non-refundable up-front received		$ 5,000,000.0
Non-refundable milestone payment	$ 2,500,000	$ 2,500,000
Revenue recognized related to upfront and milestone payments							900,000	$ 500,000
Deferred revenue					$ 5,700,000		$ 5,700,000		$ 6,600,000	6,600,000	5,700,000	$ 6,600,000	$ 5,700,000
Non-refundable up-front received period		6 months
HLS | Out-licenses | Licensing Revenue
License And Collaboration Agreements [Line Items]
Licenses revenue										$ 900,000	$ 1,800,000
HLS | Out-licenses | Maximum
License And Collaboration Agreements [Line Items]
Additional upfront payment eligible to receive based on development, regulatory and sales Milestone		$ 57,500,000