Segment Information - Schedule of the Reportable Segment and Includes the Reconciliation to Consolidated Net Loss (Details) - USD ($) $ in Thousands		3 Months Ended				6 Months Ended
		Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024
Segment Reporting Information [Line Items]
Revenue		$ 150,042		$ 87,166		$ 271,505	$ 162,165
Cost of revenue (excluding amortization and depreciation)		13,448		8,055		23,237	14,352
Research and development expense recognized		49,541		49,853		94,326	86,683
Other research and development	[1]	3,229		2,573		7,198	5,119
General and administrative expense (excluding share-based compensation expense)		13,234		12,688		24,884	24,840
Selling and marketing expense (excluding share-based compensation expense)		99,376		74,556		191,664	145,752
Stock-based compensation expense		24,611		21,382		47,919	41,572
Loss (Gain) in fair value of contingent consideration		(8,102)		2,160		(6,590)	748
Interest expense, net	[2]	1,834		1,299		4,265	2,381
Other segment items	[3]	11,014		1,590		12,586	3,179
Segment net loss		(47,973)		(79,345)		(107,386)	(147,702)
Reconciliation of net loss
Adjustments and reconciling items		0		0		0	0
Net loss		(47,973)	$ (59,413)	(79,345)	$ (68,357)	(107,386)	(147,702)
Solriamfetol
Segment Reporting Information [Line Items]
Research and development expense recognized		10,770		15,633		22,576	24,197
AXS-05
Segment Reporting Information [Line Items]
Research and development expense recognized		14,564		15,763		29,041	29,288
AXS-07
Segment Reporting Information [Line Items]
Research and development expense recognized		6,075		3,973		10,554	6,945
AXS-12
Segment Reporting Information [Line Items]
Research and development expense recognized		1,737		3,078		4,146	5,124
AXS-14
Segment Reporting Information [Line Items]
Research and development expense recognized		$ 6,225		$ 3,761		$ 7,411	$ 6,370

[1] Other research and development expenses primarily consist of facilities charges, third party consultant costs, costs related to other product candidates, and other unallocated costs.

[2] Interest expense, net of $1,834 for the three months ended June 30, 2025 comprises (i) consolidated interest expense of $4,086 and (ii) consolidated interest income of $2,252. Interest expense, net of $4,265 for the six months ended June 30, 2025 comprises (i) consolidated interest expense of $9,344 and (ii) consolidated interest income of $5,079. Interest expense, net of $1,299 for the three months ended June 30, 2024 comprises (i) consolidated interest expense of $5,079 and (ii) consolidated interest income of $3,780. Interest expense, net of $2,381 for the six months ended June 30, 2024 comprises (i) consolidated interest expense of $10,485 and (ii) consolidated interest income of $8,104.

[3] Other segment items included in Segment net loss include intangible asset amortization, loss on debt extinguishment, and other miscellaneous items.