Significant Accounting Policies	3 Months Ended
Jun. 30, 2014
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies Basis of Presentation: The condensed consolidated financial statements of McKesson Corporation (“McKesson,” the “Company,” or “we” and other similar pronouns) include the financial statements of all wholly-owned subsidiaries and majority‑owned or controlled companies. We also evaluate our ownership, contractual and other interests in entities to determine if they are variable interest entities (“VIEs”), if we have a variable interest in those entities and the nature and extent of those interests. These evaluations are highly complex and involve judgment and the use of estimates and assumptions based on available historical information and management’s judgment, among other factors. Based on our evaluations, if we determine we are the primary beneficiary of such VIEs, we consolidate such entities into our financial statements. Investments in business entities in which we do not have control, but have the ability to exercise significant influence over operating and financial policies, are accounted for using the equity method and our proportionate share of income or loss is recorded in other income, net. Intercompany transactions and balances have been eliminated. The condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States 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 footnote disclosures normally included in the annual consolidated financial statements. 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. In our opinion, the accompanying unaudited condensed consolidated financial statements include all normal recurring adjustments necessary for a fair presentation of our financial position, results of operations and cash flows for the interim periods presented. The results of operations for the quarter ended June 30, 2014 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 our Annual Report on Form 10-K for the fiscal year ended March 31, 2014 previously filed with the SEC on May 14, 2014 (“2014 Annual Report”). Certain prior period amounts have been reclassified to conform to the current period presentation. 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. Recently Adopted Accounting Pronouncements Cumulative Translation Adjustments: In the first quarter of 2015, we adopted amended guidance for parent’s accounting for the cumulative translation adjustment upon derecognition of certain subsidiaries or group of assets within a foreign entity or of an investment in a foreign entity. The amended guidance requires the release of any cumulative translation adjustment into net income only upon complete or substantially complete liquidation of a controlling interest in a subsidiary or a group of assets within a foreign entity. Also, it requires the release of all or a pro rata portion of the cumulative translation adjustment to net income in case of sale of an equity method investment that is a foreign entity. The adoption of this amended guidance did not have a material effect on our condensed financial statements. Recently Issued Accounting Pronouncements Not Yet Adopted Discontinued Operations: In April 2014, amended guidance was issued for reporting of discontinued operations and disclosures of disposals of components. The amended guidance raises the threshold for disposals to qualify as discontinued operations and permits significant continuing involvement and continuing cash flows with the discontinued operation. In addition, the amended guidance requires additional disclosures for discontinued operations and new disclosures for individually material disposal transactions that do not meet the definition of a discontinued operation. The amended guidance is effective for us prospectively commencing in the first quarter of 2016. Early adoption is permitted. We are currently evaluating the impact of this amended guidance on our consolidated financial statements. Revenue Recognition: In May 2014, amended guidance was issued for recognizing revenue from contracts with customers. The amended guidance eliminated industry specific guidance and applies to all companies. Revenues will be recognized when an entity satisfies a performance obligation by transferring control of a promised good or service to a customer in an amount that reflects the consideration to which the entity expects to be entitled for that good or service. Revenue from a contract that contains multiple performance obligations is allocated to each performance obligation generally on a relative standalone selling price basis. The amended guidance also requires additional quantitative and qualitative disclosures. The amended guidance is effective for us commencing in the first quarter of 2018. The amended guidance allows for either full retrospective adoption or modified retrospective adoption. Early adoption is not permitted. We are currently evaluating the impact of this amended guidance on our consolidated financial statements.

Significant Accounting Policies

Basis of Presentation: The condensed consolidated financial statements of McKesson Corporation (“McKesson,” the “Company,” or “we” and other similar pronouns) include the financial statements of all wholly-owned subsidiaries and majority‑owned or controlled companies. We also evaluate our ownership, contractual and other interests in entities to determine if they are variable interest entities (“VIEs”), if we have a variable interest in those entities and the nature and extent of those interests. These evaluations are highly complex and involve judgment and the use of estimates and assumptions based on available historical information and management’s judgment, among other factors. Based on our evaluations, if we determine we are the primary beneficiary of such VIEs, we consolidate such entities into our financial statements. Investments in business entities in which we do not have control, but have the ability to exercise significant influence over operating and financial policies, are accounted for using the equity method and our proportionate share of income or loss is recorded in other income, net. Intercompany transactions and balances have been eliminated. The condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States 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 footnote disclosures normally included in the annual consolidated financial statements.

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. In our opinion, the accompanying unaudited condensed consolidated financial statements include all normal recurring adjustments necessary for a fair presentation of our financial position, results of operations and cash flows for the interim periods presented.

The results of operations for the quarter ended June 30, 2014 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 our Annual Report on Form 10-K for the fiscal year ended March 31, 2014 previously filed with the SEC on May 14, 2014 (“2014 Annual Report”).

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

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.

Recently Adopted Accounting Pronouncements

Cumulative Translation Adjustments: In the first quarter of 2015, we adopted amended guidance for parent’s accounting for the cumulative translation adjustment upon derecognition of certain subsidiaries or group of assets within a foreign entity or of an investment in a foreign entity. The amended guidance requires the release of any cumulative translation adjustment into net income only upon complete or substantially complete liquidation of a controlling interest in a subsidiary or a group of assets within a foreign entity. Also, it requires the release of all or a pro rata portion of the cumulative translation adjustment to net income in case of sale of an equity method investment that is a foreign entity. The adoption of this amended guidance did not have a material effect on our condensed financial statements.

Recently Issued Accounting Pronouncements Not Yet Adopted

Discontinued Operations: In April 2014, amended guidance was issued for reporting of discontinued operations and disclosures of disposals of components. The amended guidance raises the threshold for disposals to qualify as discontinued operations and permits significant continuing involvement and continuing cash flows with the discontinued operation. In addition, the amended guidance requires additional disclosures for discontinued operations and new disclosures for individually material disposal transactions that do not meet the definition of a discontinued operation. The amended guidance is effective for us prospectively commencing in the first quarter of 2016. Early adoption is permitted. We are currently evaluating the impact of this amended guidance on our consolidated financial statements.

Revenue Recognition: In May 2014, amended guidance was issued for recognizing revenue from contracts with customers. The amended guidance eliminated industry specific guidance and applies to all companies. Revenues will be recognized when an entity satisfies a performance obligation by transferring control of a promised good or service to a customer in an amount that reflects the consideration to which the entity expects to be entitled for that good or service. Revenue from a contract that contains multiple performance obligations is allocated to each performance obligation generally on a relative standalone selling price basis. The amended guidance also requires additional quantitative and qualitative disclosures. The amended guidance is effective for us commencing in the first quarter of 2018. The amended guidance allows for either full retrospective adoption or modified retrospective adoption. Early adoption is not permitted. We are currently evaluating the impact of this amended guidance on our consolidated financial statements.