Segment Information - Schedule of Reconciliation to the Consolidated Net Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Revenues	$ 41,243	$ 86,455	$ 7,686
Cost of revenues	9,444	2,159	813
Non-program Expenses	85,405	113,388	96,825
Restructuring	21,854	33,386
Net loss	(400,666)	(541,489)	(532,784)
Corporate and Reconciling Items [Member]
Segment Reporting Information [Line Items]
Revenues	41,243	86,455	7,686
Cost of revenues	9,444	2,159	813
People and staff augmentation	165,158	220,188	195,214
Restructuring	21,854	33,386
Other segment items	22,767	34,169	47,400
Net loss	(400,666)	(541,489)	(532,784)
Corporate and Reconciling Items [Member] | ZULRESSO [Member]
Segment Reporting Information [Line Items]
Total program expenses	5,101	4,395	17,083
Corporate and Reconciling Items [Member] | zuranolone (ZURZUVAE) [Member]
Segment Reporting Information [Line Items]
Total program expenses	30,482	94,174	68,155
Corporate and Reconciling Items [Member] | SAGE-324 [Member]
Segment Reporting Information [Line Items]
Total program expenses	10,173	16,574	14,646
Corporate and Reconciling Items [Member] | dalzanemdor (SAGE-718) [Member]
Segment Reporting Information [Line Items]
Total program expenses	58,248	56,536	50,584
Corporate and Reconciling Items [Member] | Other research and development programs [Member]
Segment Reporting Information [Line Items]
Total program expenses	$ 33,277	$ 52,975	$ 49,750