Agreements - Summary of Aggregate Amount Paid for the Assets Acquired (Parenthetical) (Detail) - U.S. Rights for FYCOMPA [Member] $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($)
Asset Acquisition [Line Items]
Transaction expenses	$ 5,870	[1]
Cash [Member]
Asset Acquisition [Line Items]
Transaction expenses	$ 5,900

[1] As of September 30, 2023 the full $5.9 million has been paid in cash