Commitments and Contingent Liabilities - Narrative (Details)	Jun. 09, 2020 USD ($)	Apr. 22, 2020	Oct. 21, 2019 USD ($) company state_attorney	May 17, 2013 USD ($)	Jul. 31, 2020 state	Jun. 30, 2020 state_attorney case company state	Mar. 31, 2020 county	Jan. 14, 2020 company	Dec. 31, 2019 complaint	Nov. 30, 2019 complaint	Oct. 31, 2019 complaint	Aug. 13, 2019 fax_number fax
In re: National Prescription Opioid Litigation
Loss Contingencies [Line Items]
Complaints filed against the entity | case						2,800
In re McKesson Corporation Stockholder Derivative Litigation
Loss Contingencies [Line Items]
Proceeds from insurance carriers, net	$ 131,000,000
Effective period of governance enhancement		4 years
True Health Chiropractic Inc., et al. v. McKesson Corporation, et al
Loss Contingencies [Line Items]
Number of faxes remaining in the 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]
Statutory damages sought per violation				$ 500
True Health Chiropractic Inc., et al. v. McKesson Corporation, et al | Maximum
Loss Contingencies [Line Items]
Statutory damages sought per violation				$ 1,500
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]
Complaints filed against the entity | complaint										3	3
Consolidated Actions
Loss Contingencies [Line Items]
Complaints filed against the entity | complaint									6
United States ex rel. Hart v. McKesson Corporation, et al., 15-cv-00903-RA | Subsequent Event
Loss Contingencies [Line Items]
Number of states represented | state					27
Pending
Loss Contingencies [Line Items]
Complaints filed against the entity | case						360
Number of states in which court cases are pending | state						37
Number of attorney generals that have filed claims | state_attorney						26
Number of county government plaintiffs | county							2
Number of other large distributors named in action | company						2
Pending | In re: National Prescription Opioid Litigation
Loss Contingencies [Line Items]
Number of cases selected for possible remand to other federal courts | case						3
Number of largest pharmaceutical distributors to adopt anti-diversion programs under proposed framework | company			3
Number of state attorneys general involved in resolution discussions | state_attorney			4
Award payable under proposed framework			$ 6,900,000,000
Period over which award would be payable under proposed framework			18 years
Pending | Three Largest U.S. Pharmaceutical Distributors | In re: National Prescription Opioid Litigation
Loss Contingencies [Line Items]
Number of largest pharmaceutical distributors to adopt anti-diversion programs under proposed framework | company			3					3
Award payable under proposed framework			$ 18,000,000,000.0
Period over which award would be payable under proposed framework			18 years