Other Consolidated Financial Statement Detail (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Other Income (Expense), Net
Interest income	$ (20.1)	$ (75.9)	$ (37.5)	$ (156.8)
Interest expense	61.3	49.1	130.5	111.6
(Gains) losses on investments, net	30.7	(105.4)	61.3	(27.7)
Foreign exchange (gains) losses, net	11.3	8.7	20.7	19.4
Other, net	2.0	2.3	3.9	1.7
Other (income) expense	85.2	(121.2)	178.9	(51.8)
Equity Securities, FV-NI, Gain (Loss), Alternative [Abstract]
Net (gains) losses recognized on equity securities	30.4	(106.5)	61.0	(28.4)
Less: Net (gains) losses realized on equity securities	0.6	(0.7)	5.5	0.9
Net unrealized (gains) losses recognized on equity securities	29.8	(105.8)	55.5	(29.3)
Accrued Expenses and Other
Revenue-related reserves for discounts and allowances	1,116.0		1,116.0		$ 1,062.0
Employee compensation and benefits	228.3		228.3		335.1
Collaboration expense	319.4		319.4		214.6
Royalties and licensing fees	193.0		193.0		191.5
Reata related accrued expense	77.4		77.4		117.5
Other	689.5		689.5		838.4
Total accrued expense and other	2,472.1		2,472.1		2,623.6
Ionis, Sangamo, Denali and Sage
Equity Securities, FV-NI, Gain (Loss), Alternative [Abstract]
Net unrealized (gains) losses recognized on equity securities	51.4	$ 117.7	68.3	$ 78.0
Component of accrued expenses and other
Accrued Expenses and Other
Revenue-related reserves for discounts and allowances	$ 964.5		$ 964.5		$ 926.5