Divestitures (Details) $ in Millions		3 Months Ended				12 Months Ended
	Nov. 29, 2022 USD ($)	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Oct. 01, 2023 product
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of assets and subsidiaries		$ 240.6		$ 0.0
Other Nonoperating Income (Expense)		139.1		69.9
Gain (Loss) on Disposition of Business		70.4		0.0
Biocon Biologics
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity Securities, FV-NI, Gain (Loss)		(46.9)		2.6
Licensing Agreements
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Write down of intangible assets				32.0	$ 172.9
Disposal Group, Held-for-Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets held for sale		1,846.5	$ 1,946.0				$ 1,946.0
Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number Of Women's Healthcare Products Sold | product								2
Upjohn Distributor Markets | Disposal Group, Held-for-Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset Impairment Charges					374.2		136.4
Inventory Valuation Reserves				9.2
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal							85.2
Upjohn Distributor Markets | Disposal Group, Held-for-Sale, Not Discontinued Operations | Inventories
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset Impairment Charges					84.3
Upjohn Distributor Markets | Disposal Group, Held-for-Sale, Not Discontinued Operations | Emerging Markets Segment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Goodwill, Impairment Loss					$ 117.0
Biocon Biologics
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Other Nonoperating Income (Expense)		13.4		$ 45.7
Biocon Biologics | Scenario, Forecast | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Divestiture of Business, Deferred Cash Consideration.						$ 335.0
Biocon Biologics | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Consideration	$ 3,000.0
Proceeds from sale of assets and subsidiaries	2,000.0
Noncash or Part Noncash Divestiture, Amount of Consideration Received	$ 1,000.0
Disposal Group, Including Discontinued Operation, Ownership Percentage in Disposed Asset	12.90%
Disposal Group, Including Discontinued Operations, Contingent Consideration Liability, Working Capital Adjustment	$ 250.0
Disposal Group, Including Discontinued Operations, Contingent Consideration Paid							220.0
Women's Health Products | Disposal Group, Disposed of by Sale, Not Discontinued Operations | Other Income
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (Loss) on Disposition of Business							80.8
Women's Health Products | Disposal Group, Disposed of by Sale, Not Discontinued Operations | Selling, General and Administrative Expenses
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (Loss) on Disposition of Business							$ 156.2
OTC Business | Disposal Group, Held-for-Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset Impairment Charges			734.7
Goodwill, Impairment Loss			580.1
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down			$ 154.7
API Business | Disposal Group, Held-for-Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down		$ 10.4