Commitments and Contingent Liabilities - Narrative (Details) $ in Millions									9 Months Ended		12 Months Ended
	Jan. 28, 2022 USD ($) distributor	Jan. 25, 2022 USD ($)	Jan. 24, 2022 USD ($) distributor	Sep. 28, 2021 USD ($) distributor	Sep. 20, 2021 USD ($)	Jul. 21, 2021 USD ($) distributor	Jul. 20, 2021 USD ($) distributor	Apr. 16, 2013 state relator defendant	Dec. 31, 2021 USD ($) case state stateAttorney	Dec. 31, 2020 USD ($)	Mar. 31, 2021 USD ($)	Jan. 26, 2022 territory state	Sep. 04, 2021 state	Dec. 30, 2017 investmentFund	Dec. 29, 2017 investmentFund
National Prescription Opioid Litigation
Loss Contingencies [Line Items]
Pre-tax expenses related to estimated litigation liability									$ 193		$ 8,100
After-tax expenses related to estimated litigation liability									160	$ 6,700	$ 6,800
Total litigation liabilities									$ 8,213
National Prescription Opioid Litigation
Loss Contingencies [Line Items]
Complaints filed against the entity | case									2,800
Number of states in which court cases are pending | state													42
Number of other national distributors named in suit | distributor						2
Number of distributors | distributor						3
Award payable under proposed framework						$ 7,900
Portion of settlement to be paid by the Company (percent)						38.10%
Portion of settlement award to be used by state and local government for remediation (percent)						85.00%
Number of eligible states | state													49
Settlement payment					$ 354
National Prescription Opioid Litigation | Subsequent Event
Loss Contingencies [Line Items]
Number of states in which court cases are pending | state												46
Number of eligible states | state												49
Number of territories that have joined the proposed settlement agreement | territory												5
Settlement payment		$ 19
National Prescription Opioid Litigation | State of New York
Loss Contingencies [Line Items]
Number of other national distributors named in suit | distributor							2
Award payable under proposed framework							$ 450
Portion of settlement to be paid by the Company (percent)							38.10%
National Prescription Opioid Litigation | State of Ohio
Loss Contingencies [Line Items]
Number of other national distributors named in suit | distributor				2
Award payable under proposed framework				$ 336
Portion of settlement to be paid by the Company (percent)				38.10%
National Prescription Opioid Litigation | Cherokee Nation
Loss Contingencies [Line Items]
Number of other national distributors named in suit | distributor				2
Award payable under proposed framework				$ 29
Portion of settlement to be paid by the Company (percent)				38.10%
Payment term				6 years 6 months
National Prescription Opioid Litigation | State of Rhode Island | Subsequent Event
Loss Contingencies [Line Items]
Number of other national distributors named in suit | distributor			2
Award payable under proposed framework			$ 35
Portion of settlement to be paid by the Company (percent)			38.10%
National Prescription Opioid Litigation | State of Florida | Subsequent Event
Loss Contingencies [Line Items]
Number of other national distributors named in suit | distributor	2
Award payable under proposed framework	$ 530
Portion of settlement to be paid by the Company (percent)	38.10%
National Prescription Opioid Litigation | Native American Tribes Other Than Cherokee Nation
Loss Contingencies [Line Items]
Number of other national distributors named in suit | distributor				2
Award payable under proposed framework				$ 167
Portion of settlement to be paid by the Company (percent)				38.10%
Payment term				6 years
Polygon European Equity Opportunity Master Fund et al. v. McKesson Europe Holdings GmbH & Co. KGaA
Loss Contingencies [Line Items]
Number of investment funds that filed claims | investmentFund														4	2
United States ex rel. Piacentile v. Amgen Inc., et al.
Loss Contingencies [Line Items]
Loss Contingency Number of Relators | relator								2
Loss Contingency, Number of Additional Defendants | defendant								5
Loss Contingency, Number of States Filed on Behalf Of | state								21
Canada | National Prescription Opioid Litigation
Loss Contingencies [Line Items]
Complaints filed against the entity | case									4
Canada | National Prescription Opioid Litigation | Governmental entities
Loss Contingencies [Line Items]
Complaints filed against the entity | case									3
Canada | National Prescription Opioid Litigation | An individual
Loss Contingencies [Line Items]
Complaints filed against the entity | case									1
Three Largest U.S. Pharmaceutical Distributors | National Prescription Opioid Litigation
Loss Contingencies [Line Items]
Award payable under proposed framework						$ 21,000
Period over which award would be payable under proposed framework						18 years
Three National Pharmaceutical Distributors | National Prescription Opioid Litigation | State of New York
Loss Contingencies [Line Items]
Award payable under proposed framework							$ 1,200
Three National Pharmaceutical Distributors | National Prescription Opioid Litigation | State of Ohio
Loss Contingencies [Line Items]
Award payable under proposed framework				$ 881
Three National Pharmaceutical Distributors | National Prescription Opioid Litigation | Cherokee Nation
Loss Contingencies [Line Items]
Award payable under proposed framework				75
Three National Pharmaceutical Distributors | National Prescription Opioid Litigation | State of Rhode Island | Subsequent Event
Loss Contingencies [Line Items]
Award payable under proposed framework			$ 91
Three National Pharmaceutical Distributors | National Prescription Opioid Litigation | State of Florida | Subsequent Event
Loss Contingencies [Line Items]
Award payable under proposed framework	$ 1,400
Three National Pharmaceutical Distributors | National Prescription Opioid Litigation | Native American Tribes Other Than Cherokee Nation
Loss Contingencies [Line Items]
Award payable under proposed framework				$ 440
Pending
Loss Contingencies [Line Items]
Complaints filed against the entity | case									350
Number of states in which court cases are pending | state									40
Number of attorney generals that have filed claims | stateAttorney									23
Pending | Canada
Loss Contingencies [Line Items]
Complaints filed against the entity | case									4