Collaboration Agreements (Tables)

9 Months Ended

Sep. 30, 2022

Collaboration Agreement [Abstract]

Summary of Operating Expenses Category Related to Collaboration Agreement

The following table summarizes expenses related to the Biogen Collaboration Agreement that were incurred by the Company and the related reimbursement from Biogen, reflected by category of operating expenses:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2022			2021			2022			2021
	(in thousands)						(in thousands)
Expenses related to the Biogen Collaboration Agreement    incurred by Sage	$	53,139		$	50,950		$	161,111		$	149,653
Net reimbursement from Biogen reflected in the condensed    consolidated statement of operations and comprehensive    loss:
Research and development expenses		(17,867	)		(21,634	)		(57,364	)		(63,843	)
Selling, general and administrative expenses		(480	)		(2,551	)		(4,788	)		(8,780	)
		(18,347	)		(24,185	)		(62,152	)		(72,623	)
Total net expenses related to the Biogen Collaboration    Agreement in the condensed consolidated statement of    operations and comprehensive loss	$	34,792		$	26,765		$	98,959		$	77,030