Agreements - Summary of Aggregate Amount Paid for the Assets Acquired (Detail) - USD ($) $ in Thousands		1 Months Ended			9 Months Ended
		Jul. 31, 2023	Jan. 31, 2023		Sep. 30, 2023
Asset Acquisition [Line Items]
Total purchase consideration		$ 94,978
U.S. Rights for FYCOMPA [Member]
Asset Acquisition [Line Items]
Base cash payment			$ 160,000
Cash paid for pro-rated prepaid expenses			1,576
Reimbursement on base purchase price	[1]		(3,238)
Transaction costs			5,870	[2]	$ 5,900
Total purchase consideration			$ 164,208

[1] Recorded in prepaid expenses and other current assets in the accompanying consolidated balance sheet as of the acquisition date and reimbursement was fully applied as of June 30, 2023.

[2] As of September 30, 2023, the full $5.9 million was paid in cash.