Acquisitions and Other Transactions (Narrative) (Details) shares in Millions, $ in Millions			3 Months Ended		12 Months Ended
	Nov. 13, 2020 USD ($) shares	Jul. 29, 2019 USD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($)	Nov. 16, 2020 USD ($)	May 28, 2019 USD ($)
Business Acquisition [Line Items]
Goodwill			$ 11,907.3		$ 12,347.0
Finite-Lived Intangible Assets
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	15 years
Building | Minimum
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	10 years
Building | Maximum
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	20 years
Machinery and equipment
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	5 years
Upjohn Inc.
Business Acquisition [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired		43.00%
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt			13,076.2		13,076.2
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares	689.9
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable	$ 10,730.0
Business Combination, Acquisition Related Costs			59.8		602.9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Financial Assets			10,311.6		10,311.6		$ 10,730.0
Business Acquisition, Pro Forma Revenue				$ 4,439.4
Business Acquisition, Pro Forma Net Income (Loss)				$ 542.6
Goodwill			1,960.9		2,107.5
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Long-Term Debt	759.4
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	18,040.0		$ 18,040.0		$ 18,040.0
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Property, Plant, and Equipment	390.0
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Inventory	$ 1,430.0
Upjohn Inc. | Pfizer, Inc.
Business Acquisition [Line Items]
Payments for Business Separation		$ 12,000.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt						$ 13,080.0
Product | Upjohn Inc.
Business Acquisition [Line Items]
Number Of Products		20
Upjohn Inc. | Pfizer, Inc.
Business Acquisition [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent		57.00%