Other Consolidated Financial Statement Detail (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Other Income (Expense), Net
Interest income	$ (11.6)	$ (95.9)	$ (49.1)	$ (252.7)
Interest expense	59.8	63.8	190.3	175.4
(Gains) losses on investments, net	(39.1)	317.3	22.2	289.6
Foreign exchange (gains) losses, net	4.9	11.4	25.6	30.8
Other, net	0.8	3.4	4.7	5.1
Other (income) expense	14.8	300.0	193.7	248.2
Equity Securities, FV-NI, Gain (Loss), Alternative [Abstract]
Net (gains) losses recognized on equity securities	(39.1)	302.0	21.9	273.6
Less: Net (gains) losses realized on equity securities	(10.9)	4.4	(5.4)	5.3
Net unrealized (gains) losses recognized on equity securities	(28.2)	297.6	27.3	268.3
Accrued Expenses and Other
Revenue-related reserves for discounts and allowances	1,151.0		1,151.0		$ 1,062.0
Employee compensation and benefits	288.7		288.7		335.1
Collaboration expense	280.6		280.6		214.6
Royalties and licensing fees	178.7		178.7		191.5
Reata related accrued expense	82.3		82.3		117.5
Other	637.4		637.4		838.4
Total accrued expense and other	2,755.1		2,755.1		2,623.6
Ionis, Sangamo, Denali and Sage
Equity Securities, FV-NI, Gain (Loss), Alternative [Abstract]
Net unrealized (gains) losses recognized on equity securities	53.3	$ 295.6	90.2	$ 265.0
Component of accrued expenses and other
Accrued Expenses and Other
Revenue-related reserves for discounts and allowances	$ 1,000.3		$ 1,000.3		$ 926.5