Collaborative and Other Relationships - Summary of Activity Related to Sage Therapeutics (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2023
Collaborative arrangements and non-collaborative arrangement transactions
Share of net profit from sage therapeutics, Percent	50.00%		50.00%
Collaboration profit sharing/(loss reimbursement)	$ 50.5	$ 45.3	$ 164.5	$ (42.6)
Sage Therapeutics
Collaborative arrangements and non-collaborative arrangement transactions
Collaboration profit sharing/(loss reimbursement)	5.9		5.9
Sage Therapeutics | Forecast
Collaborative arrangements and non-collaborative arrangement transactions
Potential future milestone payments commitment to third party					$ 75.0
Research and development | Sage Therapeutics
Collaborative arrangements and non-collaborative arrangement transactions
Expense incurred by the collaboration	72.0	40.9	158.9	130.4
Expense reflected within statements of income	36.0	20.5	79.5	65.2
Selling, general and administrative | Sage Therapeutics
Collaborative arrangements and non-collaborative arrangement transactions
Expense incurred by the collaboration	54.0	28.5	152.3	69.9
Expense reflected within statements of income	$ 27.0	$ 14.2	$ 76.1	$ 34.9