License Agreements (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Mylan License and Supply Agreement
Other License Agreements And Acquired Product Rights [Line Items]
Milestone payment received	$ 2.2	$ 1.8	$ 2.2
TTY License and Supply Agreement
Other License Agreements And Acquired Product Rights [Line Items]
Milestone payment received	$ 1.2	$ 1.5	$ 1.2
Term of the agreement	15 years