License Agreements (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Mylan License and Supply Agreement
Other License Agreements And Acquired Product Rights [Line Items]
Milestone payment received	$ 0.8	$ 2.2	$ 1.8
TTY License and Supply Agreement
Other License Agreements And Acquired Product Rights [Line Items]
Milestone payment received	$ 1.1	$ 1.2	$ 1.5
Term of the agreement	15 years