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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, 2023	Dec. 31, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Litigation settlement agreement and settlement fees	$ 900.0	$ 0.0	$ 917.0	$ 0.0
Net unrealized (gains) losses recognized on equity securities		270.0	264.7	$ 831.4
Other long-term liabilities		781.1	944.2
Accrued income taxes		403.2	541.7
Ionis, Sangamo, Denali and Sage
Business Acquisition [Line Items]
Net unrealized (gains) losses recognized on equity securities		$ 248.5
Denali And Sangamo
Business Acquisition [Line Items]
Net unrealized (gains) losses recognized on equity securities			(278.0)
Ionis And Sage
Business Acquisition [Line Items]
Net unrealized (gains) losses recognized on equity securities			$ 27.3