Significant Accounting Policies (Policy)	9 Months Ended
Significant Accounting Policies (Policy)	Dec. 31, 2011
Significant Accounting Policies [Abstract]
Basis Of Presentation	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. 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.
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. 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.
Revenue Recognition	Revenue Recognition: On April 1, 2011, we adopted amended accounting guidance on a prospective basis for multiple-element arrangements entered into or materially modified on or after April 1, 2011. The amended guidance incorporates the use of a vendor's best estimate of selling price, if neither vendor specific objective evidence nor third party evidence of selling price exists, to allocate arrangement consideration and eliminates the use of the residual method. Implementation of this new guidance did not have a material impact on reported net revenues as compared to net revenues under previous guidance as the incorporation of the use of a vendor's best estimate of selling price and the elimination of the residual method for the allocation of arrangement consideration did not materially change how we allocate arrangement consideration to our various products and services or the amount and timing of reported net revenues. On April 1, 2011, we adopted amended guidance for certain revenue arrangements that include software elements. The guidance amends pre-existing software revenue guidance by removing from its scope tangible products that contain both software and non-software components that function together to deliver the product's functionality. The amended guidance was adopted on a prospective basis for revenue arrangements entered into or materially modified on or after April 1, 2011. The adoption of this amended guidance did not have a material effect on our condensed consolidated financial statements. On April 1, 2011, we adopted amended accounting guidance for vendors who apply the milestone method of revenue recognition to research and development arrangements. The amended guidance applies to arrangements with payments that are contingent, at inception, upon achieving substantively uncertain future events or circumstances. The amended guidance was adopted on a prospective basis for milestones achieved on or after April 1, 2011. The adoption of this amended guidance did not have a material effect on our condensed consolidated financial statements.

Disclosure of accounting policy for revenue recognition. If the entity has different policies for different types of revenue transactions, the policy for each material type of transaction is generally disclosed. If a sales transaction has multiple element arrangements (for example, delivery of multiple products, services or the rights to use assets) the disclosure may indicate the accounting policy for each unit of accounting as well as how units of accounting are determined and valued. The disclosure may encompass important judgment as to appropriateness of principles related to recognition of revenue. The disclosure also may indicate the entity's treatment of any unearned or deferred revenue that arises from the transaction.

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Disclosure of accounting policy for the use of estimates in the preparation of financial statements in conformity with generally accepted accounting principles.

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