Significant Accounting Policies (Policy)	6 Months Ended
Significant Accounting Policies (Policy)	Sep. 30, 2012
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. 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. The consolidated VIEs are not material to our condensed consolidated financial statements. 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.

Disclosure of accounting policy regarding (1) the principles it follows in consolidating or combining the separate financial statements, including the principles followed in determining the inclusion or exclusion of subsidiaries or other entities in the consolidated or combined financial statements and (2) its treatment of interests (for example, common stock, a partnership interest or other means of exerting influence) in other entities, for example consolidation or use of the equity or cost methods of accounting. The accounting policy may also address the accounting treatment for intercompany accounts and transactions, noncontrolling interest, and the income statement treatment in consolidation for issuances of stock by a subsidiary.

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-Name Accounting Research Bulletin (ARB)

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-Name Statement of Financial Accounting Standard (FAS)

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- Definition

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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