Commitments and Contingent Liabilities (Details)							1 Months Ended		12 Months Ended	17 Months Ended	40 Months Ended
	Feb. 25, 2019	Apr. 03, 2018 state city	Dec. 30, 2017 investmentFund	Dec. 29, 2017 investmentFund	May 17, 2013 USD ($)	Apr. 16, 2013 relator defendant state	Jul. 31, 2020 state	Dec. 31, 2019 complaint relator	Mar. 31, 2021 USD ($) site case company county	Mar. 31, 2021 USD ($) site case company county	Mar. 31, 2021 USD ($) site case company state stateAttorney county	Oct. 23, 2020 case	Jan. 13, 2020 case	Nov. 30, 2019 complaint	Oct. 31, 2019 complaint	Aug. 13, 2019 fax_number fax	Dec. 12, 2018 officer	Aug. 31, 2018 case softwareProduct
Loss Contingencies [Line Items]
Annual surcharge									$ 100,000,000	$ 100,000,000	$ 100,000,000
Investigation into Factors Contributing to Increase in Opioid-related Hospitalizations and Deaths
Loss Contingencies [Line Items]
Number of complaints served | case									300	300	300
Number of states filed on behalf of | state											38
Number of plaintiffs | stateAttorney											26
Number of county governments that brought case | county									2	2	2
New York Opioid Tax Surcharge
Loss Contingencies [Line Items]
After-tax charge recorded related to Company's share of the litigation settlement									$ 37,000,000
Environmental Litigation
Loss Contingencies [Line Items]
Number of sites | site									5	5	5
Remediation costs									$ 10,000,000	$ 10,000,000	$ 10,000,000
Hazardous substance sites, number | site									14
Number of sites selected for preferred remediation | site									1	1	1
Estimated environmental assessment and cleanup costs									$ 1,400,000,000
Estimated loss									$ 28,000,000	$ 28,000,000	$ 28,000,000
Environmental Litigation | Minimum
Loss Contingencies [Line Items]
Time frame of disbursements									April 2021
Environmental Litigation | Maximum
Loss Contingencies [Line Items]
Time frame of disbursements									March 2051
National Prescription Opiate Litigation
Loss Contingencies [Line Items]
Charge recorded related to Company's share of the litigation settlement									$ 8,100,000,000
After-tax charge recorded related to Company's share of the litigation settlement									$ 6,800,000,000
Canada | Investigation into Factors Contributing to Increase in Opioid-related Hospitalizations and Deaths
Loss Contingencies [Line Items]
Number of complaints served | case									3	3	3
In re: National Prescription Opiate Litigation
Loss Contingencies [Line Items]
Number of complaints served | case									2,900	2,900	2,900
In re: National Prescription Opiate Litigation | Pending Litigation
Loss Contingencies [Line Items]
Number of cases selected for remand to other federal courts | case													3
Aggregate amount expected to be paid										$ 8,000,000,000.0
Portion expected to be applied towards the opioid crisis remediation (percent)									90.00%	90.00%	90.00%
In re: National Prescription Opiate Litigation | Pending Litigation | Three Largest U.S. Pharmaceutical Distributors
Loss Contingencies [Line Items]
Number of largest distributors | company									3	3	3
Aggregate amount expected to be paid										$ 21,000,000,000.0
Expected payment period										18 years
United States ex rel. Manchester v. Purdue Pharma, L.P., et al
Loss Contingencies [Line Items]
Period within which party can be substituted	90 days
United States of America, ex rel. Carl Kelley and Michael McElligott, 19-cv-2233, and State of California, ex rel. Carl Kelley and Michael McElligott, CGC-19-576931
Loss Contingencies [Line Items]
Number of complaints served | complaint								2
Number of relators alleging violations | relator								2
Insurance Coverage Litigation
Loss Contingencies [Line Items]
Number of complaints served | case												2
True Health Chiropractic Inc., et al. v. McKesson Corporation, et al
Loss Contingencies [Line Items]
Number of faxes remaining in class | fax_number																9,490
Number of faxes received | fax																48,769
True Health Chiropractic Inc., et al. v. McKesson Corporation, et al | Minimum
Loss Contingencies [Line Items]
Damages sought per violation					$ 500
True Health Chiropractic Inc., et al. v. McKesson Corporation, et al | Maximum
Loss Contingencies [Line Items]
Damages sought per violation					$ 1,500
Polygon European Equity Opportunity Master Fund et al. v. McKesson Europe Holdings GmbH & Co. KGaA
Loss Contingencies [Line Items]
Number of plaintiffs | investmentFund				2
Davidson Kempner International (BVI) Ltd., et al. v. McKesson Europe Holdings GmbH & Co. KGaA
Loss Contingencies [Line Items]
Number of plaintiffs | investmentFund			4
United States ex rel. Piacentile v. Amgen Inc., et al.
Loss Contingencies [Line Items]
Number of states filed on behalf of | state						21
Number of relators alleging violations | relator						2
Number of other defendants in case | defendant						5
United States ex rel. Omni Healthcare Inc. v. McKesson Corporation, et al.
Loss Contingencies [Line Items]
Number of states filed on behalf of | state		30
Number of cities filed on behalf of | city		2
Evanston Police Pension Fund v. McKesson Corporation
Loss Contingencies [Line Items]
Number of former officers | officer																	2
Powell Prescription Center, et al. v. Surescripts, LLC, et al., and Intergrated Pharmaceutical Solutions LLC v. Surescripts, LLC
Loss Contingencies [Line Items]
Number of complaints served | complaint															3
Kennebunk Village Pharmacy, Inc. v. SureScripts, LLC, et al., 1:19-cv-7445; Whitman v. SureScripts, LLC et al., No. 1:19-cv-7448; BBK Global Corp. v. SureScripts, LLC et al., 1:19-cv-7640
Loss Contingencies [Line Items]
Number of complaints served | complaint														3
United States ex rel. Hart v. McKesson Corporation, et al., 15-cv-00903-RA
Loss Contingencies [Line Items]
Number of states filed on behalf of | state							27
Consolidated Actions v SureScripts, LLC
Loss Contingencies [Line Items]
Number of complaints served | complaint								6
Civil Investigative Demands by the U.S. Attorney’s Office for the Eastern District of New York
Loss Contingencies [Line Items]
Number of complaints served | case																		2
Number of software products | softwareProduct																		2