Significant Accounting Policies (Policies)	9 Months Ended
Dec. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation: The condensed consolidated financial statements of McKesson include the financial statements of all wholly-owned subsidiaries and majority-owned or controlled companies. For those consolidated subsidiaries where the Company’s ownership is less than 100%, the portion of the net income or loss allocable to the noncontrolling interests is reported as “Net income attributable to noncontrolling interests” in the Condensed Consolidated Statements of Operations. All significant intercompany balances and transactions have been eliminated in consolidation including the intercompany portion of transactions with equity method investees. The Company considers itself to control an entity if it is the majority owner of or has voting control over such entity. The Company also assesses control through means other than voting rights and determines which business entity is the primary beneficiary of the variable interest entity (“VIE”). The Company consolidates VIEs when it is determined that it is the primary beneficiary of the VIE. Investments in business entities in which the Company does not have control but has the ability to exercise significant influence over operating and financial policies are accounted for using the equity method. The condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S.”) of America (“GAAP”) for interim financial reporting and the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) and therefore do not include all information and disclosures normally included in the annual consolidated financial statements.
Use of Estimates	To prepare the financial statements in conformity with GAAP, management must make estimates and assumptions that affect the reported amounts of assets and liabilities as of the date of these financial statements and income and expenses during the reporting period. Actual amounts may differ from these estimated amounts. The Company continues to evaluate the ongoing impacts, including the economic consequences, of the coronavirus disease 2019 (“COVID-19”) pandemic. As COVID-19 further evolves, the Company’s accounting estimates and assumptions may change over time and may change materially in future periods. In the opinion of management, the unaudited condensed consolidated financial statements include all normal recurring adjustments necessary for a fair presentation of the financial position, results of operations, and cash flows of McKesson for the interim periods presented.
Results of Operations	The results of operations for the three and nine months ended December 31, 2021 are not necessarily indicative of the results that may be expected for the entire year. These interim financial statements should be read in conjunction with the annual audited financial statements, accounting policies, and financial notes included in the Company’s Annual Report on Form 10-K for the fiscal year ended March 31, 2021, previously filed with the SEC on May 12, 2021 (“2021 Annual Report”).
Fiscal Period	The Company’s fiscal year begins on April 1 and ends on March 31. Unless otherwise noted, all references to a particular year shall mean the Company’s fiscal year.
Reclassification	Certain prior year amounts have been reclassified to conform to the current year presentation.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In the first quarter of 2022, the Company prospectively adopted Accounting Standards Update (“ASU”) 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which eliminates certain exceptions related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period, and the recognition of deferred tax liabilities for outside basis differences. The guidance also simplifies and clarifies certain other aspects of accounting for income taxes. The adoption of this amended guidance did not have a material impact on the Company’s condensed consolidated financial statements or disclosures.
Held for Sale	Assets and liabilities of certain European businesses to be disposed of by sale (“disposal groups”) are classified as “held for sale” if their carrying amounts are principally expected to be recovered through a sale transaction rather than through continuing use. The classification occurs when the disposal group is available for immediate sale and the sale is probable. These criteria are generally met when an agreement to sell exists, or management has committed to a plan to sell the assets within one year. Disposal groups are measured at the lower of carrying amount or fair value less costs to sell, and long-lived assets included within the disposal group are not depreciated or amortized. The fair value of a disposal group, less any costs to sell, is assessed each reporting period it remains classified as held for sale and any remeasurement to the lower of carrying value or fair value less costs to sell is reported as an adjustment to the carrying value of the disposal group.
Commitments and Contingencies	In addition to commitments and obligations incurred in the ordinary course of business, the Company is subject to a variety of claims and legal proceedings, including claims from customers and vendors, pending and potential legal actions for damages, governmental investigations, and other matters. The Company and its affiliates are parties to the legal claims and proceedings described below and in Financial Note 19 to the Company’s 2021 Annual Report, which disclosure is incorporated in this footnote by this reference. The Company is vigorously defending itself against those claims and in those proceedings. Significant developments in those matters are described below. If the Company is unsuccessful in defending, or if it determines to settle, any of these matters, it may be required to pay substantial sums, be subject to injunction and/or be forced to change how it operates its business, which could have a material adverse impact on its financial position or results of operations. Unless otherwise stated, the Company is unable to reasonably estimate the loss or a range of possible loss for the matters described below. Often, the Company is unable to determine that a loss is probable, or to reasonably estimate the amount of loss or a range of loss, for a claim because of the limited information available and the potential effects of future events and decisions by third parties, such as courts and regulators, that will determine the ultimate resolution of the claim. Many of the matters described are at preliminary stages, raise novel theories of liability, or seek an indeterminate amount of damages. It is not uncommon for claims to remain unresolved over many years. The Company reviews loss contingencies at least quarterly to determine whether the likelihood of loss has changed and whether it can make a reasonable estimate of the loss or range of loss. When the Company determines that a loss from a claim is probable and reasonably estimable, it records a liability for an estimated amount. The Company also provides disclosure when it is reasonably possible that a loss may be incurred or when it is reasonably possible that the amount of a loss will exceed its recorded liability. Amounts included within “Claims and litigation charges, net” in the Condensed Consolidated Statement of Operations consist of estimated loss contingencies related to opioid-related litigation matters.

Significant Accounting Policies (Policies)

9 Months Ended

Dec. 31, 2021

Basis of Presentation: The condensed consolidated financial statements of McKesson include the financial statements of all wholly-owned subsidiaries and majority-owned or controlled companies. For those consolidated subsidiaries where the Company’s ownership is less than 100%, the portion of the net income or loss allocable to the noncontrolling interests is reported as “Net income attributable to noncontrolling interests” in the Condensed Consolidated Statements of Operations. All significant intercompany balances and transactions have been eliminated in consolidation including the intercompany portion of transactions with equity method investees.

The Company considers itself to control an entity if it is the majority owner of or has voting control over such entity. The Company also assesses control through means other than voting rights and determines which business entity is the primary beneficiary of the variable interest entity (“VIE”). The Company consolidates VIEs when it is determined that it is the primary beneficiary of the VIE. Investments in business entities in which the Company does not have control but has the ability to exercise significant influence over operating and financial policies are accounted for using the equity method.

The condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S.”) of America (“GAAP”) for interim financial reporting and the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) and therefore do not include all information and disclosures normally included in the annual consolidated financial statements.

Use of Estimates

To prepare the financial statements in conformity with GAAP, management must make estimates and assumptions that affect the reported amounts of assets and liabilities as of the date of these financial statements and income and expenses during the reporting period. Actual amounts may differ from these estimated amounts. The Company continues to evaluate the ongoing impacts, including the economic consequences, of the coronavirus disease 2019 (“COVID-19”) pandemic. As COVID-19 further evolves, the Company’s accounting estimates and assumptions may change over time and may change materially in future periods. In the opinion of management, the unaudited condensed consolidated financial statements include all normal recurring adjustments necessary for a fair presentation of the financial position, results of operations, and cash flows of McKesson for the interim periods presented.

Results of Operations

The results of operations for the three and nine months ended December 31, 2021 are not necessarily indicative of the results that may be expected for the entire year. These interim financial statements should be read in conjunction with the annual audited financial statements, accounting policies, and financial notes included in the Company’s Annual Report on Form 10-K for the fiscal year ended March 31, 2021, previously filed with the SEC on May 12, 2021 (“2021 Annual Report”).

Fiscal Period

The Company’s fiscal year begins on April 1 and ends on March 31. Unless otherwise noted, all references to a particular year shall mean the Company’s fiscal year.

Reclassification

Certain prior year amounts have been reclassified to conform to the current year presentation.

Recently Adopted Accounting Pronouncements

In the first quarter of 2022, the Company prospectively adopted Accounting Standards Update (“ASU”) 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which eliminates certain exceptions related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period, and the recognition of deferred tax liabilities for outside basis differences. The guidance also simplifies and clarifies certain other aspects of accounting for income taxes. The adoption of this amended guidance did not have a material impact on the Company’s condensed consolidated financial statements or disclosures.

Held for Sale

Assets and liabilities of certain European businesses to be disposed of by sale (“disposal groups”) are classified as “held for sale” if their carrying amounts are principally expected to be recovered through a sale transaction rather than through continuing use. The classification occurs when the disposal group is available for immediate sale and the sale is probable. These criteria are generally met when an agreement to sell exists, or management has committed to a plan to sell the assets within one year. Disposal groups are measured at the lower of carrying amount or fair value less costs to sell, and long-lived assets included within the disposal group are not depreciated or amortized. The fair value of a disposal group, less any costs to sell, is assessed each reporting period it remains classified as held for sale and any remeasurement to the lower of carrying value or fair value less costs to sell is reported as an adjustment to the carrying value of the disposal group.

Commitments and Contingencies

In addition to commitments and obligations incurred in the ordinary course of business, the Company is subject to a variety of claims and legal proceedings, including claims from customers and vendors, pending and potential legal actions for damages, governmental investigations, and other matters. The Company and its affiliates are parties to the legal claims and proceedings described below and in Financial Note 19 to the Company’s 2021 Annual Report, which disclosure is incorporated in this footnote by this reference. The Company is vigorously defending itself against those claims and in those proceedings. Significant developments in those matters are described below. If the Company is unsuccessful in defending, or if it determines to settle, any of these matters, it may be required to pay substantial sums, be subject to injunction and/or be forced to change how it operates its business, which could have a material adverse impact on its financial position or results of operations.

Unless otherwise stated, the Company is unable to reasonably estimate the loss or a range of possible loss for the matters described below. Often, the Company is unable to determine that a loss is probable, or to reasonably estimate the amount of loss or a range of loss, for a claim because of the limited information available and the potential effects of future events and decisions by third parties, such as courts and regulators, that will determine the ultimate resolution of the claim. Many of the matters described are at preliminary stages, raise novel theories of liability, or seek an indeterminate amount of damages. It is not uncommon for claims to remain unresolved over many years. The Company reviews loss contingencies at least quarterly to determine whether the likelihood of loss has changed and whether it can make a reasonable estimate of the loss or range of loss. When the Company determines that a loss from a claim is probable and reasonably estimable, it records a liability for an estimated amount. The Company also provides disclosure when it is reasonably possible that a loss may be incurred or when it is reasonably possible that the amount of a loss will exceed its recorded liability. Amounts included within “Claims and litigation charges, net” in the Condensed Consolidated Statement of Operations consist of estimated loss contingencies related to opioid-related litigation matters.