Summary of Significant Accounting Policies - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Disaggregation Of Revenue [Line Items]
Total net revenues	$ 129,071	$ 152,967
Ampyra
Disaggregation Of Revenue [Line Items]
Total net revenues	84,555	98,887
Inbrija
Disaggregation Of Revenue [Line Items]
Total net revenues	29,634	24,233
Other
Disaggregation Of Revenue [Line Items]
Total net revenues		1,711
Net Product Revenues
Disaggregation Of Revenue [Line Items]
Total net revenues	114,189	124,831
Milestone Revenue [Member]
Disaggregation Of Revenue [Line Items]
Total net revenues		15,000
Royalty Revenues
Disaggregation Of Revenue [Line Items]
Total net revenues	$ 14,882	$ 13,136