SEGMENT INFORMATION (Details) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2026 USD ($)	Jun. 30, 2025 USD ($)	Jun. 30, 2026 USD ($) segment	Jun. 30, 2025 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments \| segment			1
Net product revenue	$ 261,280	$ 200,489	$ 476,667	$ 385,222
Stock-based compensation	9,576	11,394	19,884	23,844
Interest expense	3,070	3,646	6,304	7,482
Interest income	(7,072)	(5,296)	(12,829)	(10,340)
Income tax expense	17,834	9,861	25,033	21,478
Net income	75,431	39,776	107,919	85,336
Rare Neurological Diseases Segment
Segment Reporting Information [Line Items]
Net product revenue	261,280	200,489	476,667	385,222
Cost of product sold	63,191	38,147	107,696	70,134
Research and development	44,034	33,046	79,052	65,284
Sales and marketing	32,311	28,421	62,210	56,388
General and administrative	16,884	20,334	37,282	38,212
Depreciation and amortization	5,968	5,967	11,936	11,935
Stock-based compensation	9,576	11,394	19,884	23,844
Interest expense	3,070	3,646	6,304	7,482
Interest income	(7,072)	(5,296)	(12,829)	(10,340)
Income tax expense	17,834	9,861	25,033	21,478
Other segment items	$ 53	$ 15,193	$ 32,180	$ 15,469
Segment Reporting, Other Segment Item, Composition, Description	Other segment items include other expense, net and IPR&D charges	Other segment items include other expense, net and IPR&D charges	Other segment items include other expense, net and IPR&D charges	Other segment items include other expense, net and IPR&D charges
Net income	$ 75,431	$ 39,776	$ 107,919	$ 85,336

The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line. Excludes stock-based compensation, depreciation and amortization related expenses.

No definition available.