Significant Accounting Policies	9 Months Ended
Dec. 31, 2011
Significant Accounting Policies [Abstract]
Significant Accounting Policies	1. 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. 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 condensed consolidated balance sheet at March 31, 2011 has been derived from the audited consolidated financial statements at that date but does not include all the information and footnotes required by GAAP for complete financial statements. The results of operations for the quarter and nine months ended December 31, 2011 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, 2011 previously filed with the SEC on May 5, 2011 ("2011 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 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. Recently Issued Accounting Pronouncements Not Yet Adopted In May 2011, the Financial Accounting Standards Board ("FASB") issued amended accounting guidance related to fair value measurements and disclosure requirements. The amended guidance clarifies the application of existing fair value measurement requirements. The amended guidance is effective for us on a prospective basis commencing in the fourth quarter of 2012. We do not expect the adoption of the amended guidance to have a material effect on our consolidated financial statements. In June 2011, the FASB issued amended guidance related to the presentation of other comprehensive income requiring that comprehensive income, the components of net income and the components of other comprehensive income be presented either in a single continuous statement of comprehensive income or in two separate but consecutive statements. While the new guidance changes the presentation of comprehensive income, there are no changes to the components that are recognized in net income or other comprehensive income as determined under current accounting guidance. In December 2011, the FASB issued an amendment to this guidance to defer the requirement to present reclassification adjustments for each component of other comprehensive income in both net income and other comprehensive income on the face of the financial statements. The amended guidance is effective for us on a retrospective basis commencing in the first quarter of 2013. We do not expect the adoption of the amended guidance to have a material effect on our consolidated financial statements. In September 2011, the FASB issued amended accounting guidance related to goodwill impairment testing. The new guidance provides the option to perform a qualitative assessment by applying a more likely than not scenario to determine whether the fair value of a reporting unit is less than its carrying amount, which may then allow a company to skip the annual two-step quantitative goodwill impairment test depending on the determination. The amended guidance is effective for us commencing in the first quarter of 2013. Earlier adoption is permitted. We are in the process of adopting this amended guidance in 2012 and do not expect it to have a material effect on our consolidated financial statements. In September 2011, the FASB issued amended accounting guidance related to an employer's participation in a multiemployer pension and other postretirement benefit plans to require that employers provide additional quantitative and qualitative disclosures for these types of plans. The amended guidance is effective for us on a retrospective basis commencing in the fourth quarter of 2012. Earlier adoption is permitted. We are currently evaluating the impact of this new guidance on our consolidated financial statements. In December 2011, the FASB issued disclosure guidance related to the offsetting of assets and liabilities. The guidance requires an entity to disclose information about offsetting and related arrangements for recognized financial and derivative instruments to enable users of its financial statements to understand the effect of those arrangements on its financial position. The amended guidance is effective for us on a retrospective basis commencing in the first quarter of 2014. We are currently evaluating the impact of this new guidance on our consolidated financial statements.

1. 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. 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 condensed consolidated balance sheet at March 31, 2011 has been derived from the audited consolidated financial statements at that date but does not include all the information and footnotes required by GAAP for complete financial statements.

The results of operations for the quarter and nine months ended December 31, 2011 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, 2011 previously filed with the SEC on May 5, 2011 ("2011 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

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.

Recently Issued Accounting Pronouncements Not Yet Adopted

In May 2011, the Financial Accounting Standards Board ("FASB") issued amended accounting guidance related to fair value measurements and disclosure requirements. The amended guidance clarifies the application of existing fair value measurement requirements. The amended guidance is effective for us on a prospective basis commencing in the fourth quarter of 2012. We do not expect the adoption of the amended guidance to have a material effect on our consolidated financial statements.

In June 2011, the FASB issued amended guidance related to the presentation of other comprehensive income requiring that comprehensive income, the components of net income and the components of other comprehensive income be presented either in a single continuous statement of comprehensive income or in two separate but consecutive statements. While the new guidance changes the presentation of comprehensive income, there are no changes to the components that are recognized in net income or other comprehensive income as determined under current accounting guidance. In December 2011, the FASB issued an amendment to this guidance to defer the requirement to present reclassification adjustments for each component of other comprehensive income in both net income and other comprehensive income on the face of the financial statements. The amended guidance is effective for us on a retrospective basis commencing in the first quarter of 2013. We do not expect the adoption of the amended guidance to have a material effect on our consolidated financial statements.

In September 2011, the FASB issued amended accounting guidance related to goodwill impairment testing. The new guidance provides the option to perform a qualitative assessment by applying a more likely than not scenario to determine whether the fair value of a reporting unit is less than its carrying amount, which may then allow a company to skip the annual two-step quantitative goodwill impairment test depending on the determination. The amended guidance is effective for us commencing in the first quarter of 2013. Earlier adoption is permitted. We are in the process of adopting this amended guidance in 2012 and do not expect it to have a material effect on our consolidated financial statements.

In September 2011, the FASB issued amended accounting guidance related to an employer's participation in a multiemployer pension and other postretirement benefit plans to require that employers provide additional quantitative and qualitative disclosures for these types of plans. The amended guidance is effective for us on a retrospective basis commencing in the fourth quarter of 2012. Earlier adoption is permitted. We are currently evaluating the impact of this new guidance on our consolidated financial statements.

In December 2011, the FASB issued disclosure guidance related to the offsetting of assets and liabilities. The guidance requires an entity to disclose information about offsetting and related arrangements for recognized financial and derivative instruments to enable users of its financial statements to understand the effect of those arrangements on its financial position. The amended guidance is effective for us on a retrospective basis commencing in the first quarter of 2014. We are currently evaluating the impact of this new guidance on our consolidated financial statements.