Intangible Assets and Goodwill - Summary of Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Finite-Lived Intangible Assets [Line Items]
Cost	$ 14,067.3	$ 14,138.4
Accumulated Amortization	6,687.8	6,254.1
Net	7,379.5	7,884.3
Intangible assets, gross (excluding goodwill)	15,866.3	15,945.3
Net	9,178.5	9,691.2
In-process research and development (omaveloxolone)
Finite-Lived Intangible Assets [Line Items]
Intangible assets (excluding goodwill)	1,635.0	1,642.9
Priority review voucher
Finite-Lived Intangible Assets [Line Items]
Intangible assets (excluding goodwill)	100.0	100.0
Trademarks and trade names
Finite-Lived Intangible Assets [Line Items]
Intangible assets (excluding goodwill)	$ 64.0	$ 64.0
Minimum | Developed technology and other
Finite-Lived Intangible Assets [Line Items]
Estimated life (in years)	1 year
Maximum | Developed technology and other
Finite-Lived Intangible Assets [Line Items]
Estimated life (in years)	30 years