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License agreement milestone payments paid.

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The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Remaining amortization period of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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INTANGIBLE ASSETS - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended				3 Months Ended
	Mar. 31, 2022	Feb. 28, 2022	Oct. 31, 2020	Aug. 31, 2019	Mar. 31, 2024	Mar. 31, 2023
Intangible Assets
Net product revenue					$ 154,615	$ 119,126
Amortization expense					$ 5,961	$ 5,961
WAKIX
Intangible Assets
Useful life of intangible asset	7 years 7 months 6 days
Remaining useful life					5 years 6 months
Final payment paid	$ 40,000
WAKIX \| United States
Intangible Assets
Net product revenue		$ 500,000
WAKIX \| Daytime Sleepiness
Intangible Assets
License agreement milestone payments paid				$ 75,000
Useful life of intangible asset				10 years
Remaining useful life					5 years 6 months
NDA for WAKIX. \| Cataplexy
Intangible Assets
License agreement milestone payments paid			$ 100,000
Useful life of intangible asset			9 years
Remaining useful life					5 years 6 months