Share-Based Payments - Summary of Share-based Compensation Expense Associated with Each Share-based Compensating Programs (Details) - USD ($) $ in Millions		12 Months Ended
	Jul. 02, 2024	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Subtotal		$ 303.5	$ 352.7	$ 668.4
Capitalized share-based compensation costs		(12.4)	(10.3)	(10.2)
Share-based compensation expense included in total cost and expense		291.1	342.4	658.2
Human Immunology Biosciences
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 56.4	0.0	56.4	0.0
Time-vested restricted stock units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense		249.3	236.4	220.0
Performance stock units settled in stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense		42.3	48.4	35.5
Performance stock units settled in cash
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense		0.0	(2.5)	6.8
Employee stock purchase plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense		8.4	9.7	10.5
Stock options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense		3.5	3.7	3.7
Market stock units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense		0.0	0.6	4.9
Equity Awards Of Acquired Company
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense		$ 0.0	$ 0.0	$ 387.0