Significant Accounting Policies (Policies)	9 Months Ended
Dec. 31, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation: The condensed consolidated financial statements and accompanying notes are prepared in accordance with United States (“U.S.”) generally accepted accounting principles (“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. 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 can exercise significant influence over operating and financial policies are accounted for using the equity method.
Fiscal Period	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	Reclassifications: Certain prior period amounts have been reclassified to conform to the current year presentation.
Use of Estimates	Use of Estimates: The preparation of financial statements in conformity with U.S. GAAP requires the Company to 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 could differ from those estimated amounts. The Company continues to evaluate the ongoing impacts, including the economic consequences, of the pandemic caused by the SARS-CoV-2 coronavirus (“COVID-19”), and therefore 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 results of operations, financial position, 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, 2022 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, 2022, previously filed with the SEC on May 9, 2022 (“2022 Annual Report”).
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements There were no adopted accounting standards during the nine months ended December 31, 2022 that had a material impact to the Company’s results of operations, financial position, cash flows, or notes to the financial statements upon their adoption. Recently Issued Accounting Pronouncements Not Yet Adopted In June 2022, the Financial Accounting Standards Board issued Accounting Standards Update (“ASU”) 2022-03, Fair Value Measurement (Topic 820): Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions, which clarifies the guidance when measuring the fair value of an equity security subject to contractual restrictions that prohibit the sale of the equity security, and requires additional disclosure requirements. ASU 2022-03 is effective for the Company on a prospective basis for fiscal years beginning after December 15, 2023, with early adoption permitted. The Company does not expect that this guidance will have a material impact on its consolidated financial statements or related disclosures
Held for Sale	Assets and liabilities 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. When the net realizable value of a disposal group increases during a period, a gain can be recognized to the extent that it does not increase the value of the disposal group beyond its original carrying value when the disposal group was classified as held for sale.
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 18 to the Company’s 2022 Annual Report, Financial Note 12 to the Company’s 10-Q filing for the quarterly period ended June 30, 2022, and Financial Note 12 to the Company’s 10-Q filing for the quarterly period ended September 30, 2022, 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 Statements of Operations consist of estimated loss contingencies related to opioid-related litigation matters.

Significant Accounting Policies (Policies)

9 Months Ended

Dec. 31, 2022

Basis of Presentation: The condensed consolidated financial statements and accompanying notes are prepared in accordance with United States (“U.S.”) generally accepted accounting principles (“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.

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 can exercise significant influence over operating and financial policies are accounted for using the equity method.

Fiscal Period

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

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

Use of Estimates

Use of Estimates: The preparation of financial statements in conformity with U.S. GAAP requires the Company to 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 could differ from those estimated amounts. The Company continues to evaluate the ongoing impacts, including the economic consequences, of the pandemic caused by the SARS-CoV-2 coronavirus (“COVID-19”), and therefore 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 results of operations, financial position, 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, 2022 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, 2022, previously filed with the SEC on May 9, 2022 (“2022 Annual Report”).

Recently Adopted Accounting Pronouncements

There were no adopted accounting standards during the nine months ended December 31, 2022 that had a material impact to the Company’s results of operations, financial position, cash flows, or notes to the financial statements upon their adoption.

Recently Issued Accounting Pronouncements Not Yet Adopted

In June 2022, the Financial Accounting Standards Board issued Accounting Standards Update (“ASU”) 2022-03, Fair Value Measurement (Topic 820): Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions, which clarifies the guidance when measuring the fair value of an equity security subject to contractual restrictions that prohibit the sale of the equity security, and requires additional disclosure requirements. ASU 2022-03 is effective for the Company on a prospective basis for fiscal years beginning after December 15, 2023, with early adoption permitted. The Company does not expect that this guidance will have a material impact on its consolidated financial statements or related disclosures

Held for Sale

Assets and liabilities 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. When the net realizable value of a disposal group increases during a period, a gain can be recognized to the extent that it does not increase the value of the disposal group beyond its original carrying value when the disposal group was classified as held for sale.

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 18 to the Company’s 2022 Annual Report, Financial Note 12 to the Company’s 10-Q filing for the quarterly period ended June 30, 2022, and Financial Note 12 to the Company’s 10-Q filing for the quarterly period ended September 30, 2022, 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 Statements of Operations consist of estimated loss contingencies related to opioid-related litigation matters.