Revenue - Narrative (Details) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2020 USD ($) payment	Dec. 31, 2023 wholesaler	Dec. 31, 2022	Dec. 31, 2021	Jul. 31, 2023
Disaggregation of Revenue [Line Items]
Number of wholesalers | wholesaler		2
Percentage of total revenues		17.20%	16.70%	15.10%
Contract manufacturing revenue
Disaggregation of Revenue [Line Items]
Remaining performance obligation, amount | $	$ 500.0
Revenue, Remaining Performance Obligation, Number Of Payments | payment	3
LEQEMBI Collaboration
Disaggregation of Revenue [Line Items]
Share of non-controling interest recognized		50.00%			50.00%
Distributor One
Disaggregation of Revenue [Line Items]
Percentage of revenue from major distributors		27.00%	26.80%	28.80%
Distributor Two
Disaggregation of Revenue [Line Items]
Percentage of revenue from major distributors		9.90%	11.10%	10.10%
Distributor One
Disaggregation of Revenue [Line Items]
Percentage receivables of wholesale distributor accounted in consolidated receivables		24.60%	22.70%
Distributor Two
Disaggregation of Revenue [Line Items]
Percentage receivables of wholesale distributor accounted in consolidated receivables		11.60%	10.90%