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Other Consolidated Financial Statement Detail - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2022	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Business Acquisition [Line Items]
Litigation settlement agreement and settlement fees	$ 900.0	$ 0.0	$ 0.0	$ 917.0
Net unrealized (gains) losses recognized on equity securities		102.4	270.0	$ 264.7
Other long-term liabilities		732.3	781.1
Accrued income taxes		156.7	403.2
Sage Therapeutics
Business Acquisition [Line Items]
Net unrealized (gains) losses recognized on equity securities		101.4
Denali And Sangamo
Business Acquisition [Line Items]
Net unrealized (gains) losses recognized on equity securities		$ 7.5	(278.0)
Ionis, Sangamo, Denali and Sage
Business Acquisition [Line Items]
Net unrealized (gains) losses recognized on equity securities			(248.5)
Ionis And Sage
Business Acquisition [Line Items]
Net unrealized (gains) losses recognized on equity securities			$ 27.3