Commitments and Contingent Liabilities	9 Months Ended
Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities	Commitments and Contingent Liabilities In addition to commitments and obligations in the ordinary course of business, we are subject to various claims, other pending and potential legal actions for damages, investigations relating to governmental laws and regulations and other matters arising out of the normal conduct of our business. As described below, many of these proceedings are at preliminary stages and many seek an indeterminate amount of damages. When a loss is considered probable and reasonably estimable, we record a liability in the amount of our best estimate for the ultimate loss. However, the likelihood of a loss with respect to a particular contingency is often difficult to predict and determining a meaningful estimate of the loss or a range of loss may not be practicable based on the information available and the potential effect of future events and decisions by third parties that will determine the ultimate resolution of the contingency. Moreover, it is not uncommon for such matters to be resolved over many years, during which time relevant developments and new information must be reevaluated at least quarterly to determine both the likelihood of potential loss and whether it is possible to reasonably estimate a range of possible loss. When a loss is probable but a reasonable estimate cannot be made, disclosure of the proceeding is provided. Disclosure also is provided when it is reasonably possible that a loss will be incurred or when it is reasonably possible that the amount of a loss will exceed the recorded provision. We review all contingencies at least quarterly to determine whether the likelihood of loss has changed and to assess whether a reasonable estimate of the loss or range of loss can be made. As discussed above, development of a meaningful estimate of loss or a range of potential loss is complex when the outcome is directly dependent on negotiations with or decisions by third parties, such as regulatory agencies, the court system and other interested parties. Such factors bear directly on whether it is possible to reasonably estimate a range of potential loss and boundaries of high and low estimates. Significant developments in previously reported proceedings and in other litigation and claims, since the filing of our 2015 Annual Report on Form 10-K and our Quarterly Report on Form 10-Q for the periods ended June 30, 2015 and September 30, 2015, are set out below. Unless otherwise stated, we are currently unable to estimate a range of reasonably possible losses for the unresolved proceedings described below. Should any one or a combination of more than one of these proceedings be successful, or should we determine to settle any or a combination of these matters, we may be required to pay substantial sums, become subject to the entry of an injunction or be forced to change the manner in which we operate our business, which could have a material adverse impact on our financial position or results of operations. Litigation, Government Subpoenas and Investigations On August 29, 2007, PSKW, LLC filed a lawsuit against McKesson Specialty Arizona Inc. in the New York Supreme Court, New York County, alleging that McKesson Specialty Arizona misappropriated trade secrets and confidential information in launching its LoyaltyScript® program, PSKW, LLC v. McKesson Specialty Arizona Inc., Index No. 602921/07. The trial began on June 22, 2015 and has concluded. Post trial briefs will be filed, with a verdict to follow. In May 2013, True Health Chiropractic, Inc. filed a class action against McKesson Corporation, claiming that McKesson sent unsolicited marketing faxes in violation of the Telephone Consumer Protection Act of 1991 (“TCPA”), as amended by the Junk Fax Protection Act of 2005 or JFPA. The case is pending in the Northern District of California. True Health Chiropractic Inc., et al. v. McKesson Corporation, et al., CV-13-02219 (HG). In August 2015, McKesson was granted a waiver from the opt out requirement from the Federal Communications Commission. Plaintiffs have appealed that decision. In September 2015, plaintiffs filed for class certification. The Court’s ruling on that motion is pending. On January 8, 2016, the state of West Virginia filed suit against the Company in state court in Boone County, West Virginia, State of West Virginia ex rel. Patrick Morrisey, Attorney General v. McKesson Corporation, Case No. 16-C-1. As with similar suits pending against other distributors, the lawsuit alleges violations of the West Virginia Controlled Substances Act, the West Virginia Consumer Credit and Protection Act, as well as common law claims for negligence, public nuisance and unjust enrichment, related to McKesson’s supply of controlled substances to West Virginia from 2007-2012, and its alleged failure to report suspicious controlled substances orders. As previously disclosed, on May 21, 2014, four hedge funds managed by Magnetar Capital filed a complaint against McKesson Deutschland GmbH & Co. KGaA (formerly known as “Dragonfly GmbH & Co KGaA”), a wholly-owned subsidiary of the Company, in a German court in Frankfurt, Germany, alleging that McKesson Deutschland violated German takeover law in connection with the Company’s acquisition of Celesio by paying more to some holders of Celesio’s convertible bonds than it paid to the shareholders of Celesio’s stock, Magnetar Capital Master Fund Ltd. et al. v. Dragonfly GmbH & Co KGaA, No. 3- 05 O 44/14. On December 5, 2014, the court dismissed Magnetar’s lawsuit. Magnetar subsequently appealed that ruling. On January 19, 2016, the appellate court issued a ruling reversing the lower court’s decision. The Company plans to appeal. From time to time, the Company receives subpoenas or requests for information from various government agencies. The Company generally responds to such subpoenas and requests in a cooperative, thorough and timely manner. These responses sometimes require time and effort and can result in considerable costs being incurred by the Company. Such subpoenas and requests also can lead to the assertion of claims or the commencement of civil or criminal legal proceedings against the Company and other members of the health care industry, as well as to settlements. Examples of such subpoenas and investigations are included in the Company’s 2015 Annual Report on Form 10-K. The Company continues to receive and respond to these requests. Value Added Tax Assessments We operate in various countries outside the United States which collect value added taxes (“VAT”). The determination of the manner in which a VAT applies to our foreign operations is subject to varying interpretations arising from the complex nature of the tax laws. We have received assessments for VAT which are in various stages of appeal. We disagree with these assessments and believe that we have strong legal arguments to defend our tax positions. Certain VAT assessments relate to years covered by an indemnification agreement. Due to the complex nature of the tax laws, it is not possible to estimate the outcome of these matters. However, based on the currently available information, we believe the ultimate outcome of these matters will not have a material adverse effect on our financial position, cash flows or results of operations.

Commitments and Contingent Liabilities

In addition to commitments and obligations in the ordinary course of business, we are subject to various claims, other pending and potential legal actions for damages, investigations relating to governmental laws and regulations and other matters arising out of the normal conduct of our business. As described below, many of these proceedings are at preliminary stages and many seek an indeterminate amount of damages.

When a loss is considered probable and reasonably estimable, we record a liability in the amount of our best estimate for the ultimate loss. However, the likelihood of a loss with respect to a particular contingency is often difficult to predict and determining a meaningful estimate of the loss or a range of loss may not be practicable based on the information available and the potential effect of future events and decisions by third parties that will determine the ultimate resolution of the contingency. Moreover, it is not uncommon for such matters to be resolved over many years, during which time relevant developments and new information must be reevaluated at least quarterly to determine both the likelihood of potential loss and whether it is possible to reasonably estimate a range of possible loss. When a loss is probable but a reasonable estimate cannot be made, disclosure of the proceeding is provided.

Disclosure also is provided when it is reasonably possible that a loss will be incurred or when it is reasonably possible that the amount of a loss will exceed the recorded provision. We review all contingencies at least quarterly to determine whether the likelihood of loss has changed and to assess whether a reasonable estimate of the loss or range of loss can be made. As discussed above, development of a meaningful estimate of loss or a range of potential loss is complex when the outcome is directly dependent on negotiations with or decisions by third parties, such as regulatory agencies, the court system and other interested parties. Such factors bear directly on whether it is possible to reasonably estimate a range of potential loss and boundaries of high and low estimates.

Significant developments in previously reported proceedings and in other litigation and claims, since the filing of our 2015 Annual Report on Form 10-K and our Quarterly Report on Form 10-Q for the periods ended June 30, 2015 and September 30, 2015, are set out below. Unless otherwise stated, we are currently unable to estimate a range of reasonably possible losses for the unresolved proceedings described below. Should any one or a combination of more than one of these proceedings be successful, or should we determine to settle any or a combination of these matters, we may be required to pay substantial sums, become subject to the entry of an injunction or be forced to change the manner in which we operate our business, which could have a material adverse impact on our financial position or results of operations.

Litigation, Government Subpoenas and Investigations

On August 29, 2007, PSKW, LLC filed a lawsuit against McKesson Specialty Arizona Inc. in the New York Supreme Court, New York County, alleging that McKesson Specialty Arizona misappropriated trade secrets and confidential information in launching its LoyaltyScript® program, PSKW, LLC v. McKesson Specialty Arizona Inc., Index No. 602921/07. The trial began on June 22, 2015 and has concluded. Post trial briefs will be filed, with a verdict to follow.

In May 2013, True Health Chiropractic, Inc. filed a class action against McKesson Corporation, claiming that McKesson sent unsolicited marketing faxes in violation of the Telephone Consumer Protection Act of 1991 (“TCPA”), as amended by the Junk Fax Protection Act of 2005 or JFPA. The case is pending in the Northern District of California. True Health Chiropractic Inc., et al. v. McKesson Corporation, et al., CV-13-02219 (HG). In August 2015, McKesson was granted a waiver from the opt out requirement from the Federal Communications Commission. Plaintiffs have appealed that decision. In September 2015, plaintiffs filed for class certification. The Court’s ruling on that motion is pending.

On January 8, 2016, the state of West Virginia filed suit against the Company in state court in Boone County, West Virginia, State of West Virginia ex rel. Patrick Morrisey, Attorney General v. McKesson Corporation, Case No. 16-C-1. As with similar suits pending against other distributors, the lawsuit alleges violations of the West Virginia Controlled Substances Act, the West Virginia Consumer Credit and Protection Act, as well as common law claims for negligence, public nuisance and unjust enrichment, related to McKesson’s supply of controlled substances to West Virginia from 2007-2012, and its alleged failure to report suspicious controlled substances orders.

As previously disclosed, on May 21, 2014, four hedge funds managed by Magnetar Capital filed a complaint against McKesson Deutschland GmbH & Co. KGaA (formerly known as “Dragonfly GmbH & Co KGaA”), a wholly-owned subsidiary of the Company, in a German court in Frankfurt, Germany, alleging that McKesson Deutschland violated German takeover law in connection with the Company’s acquisition of Celesio by paying more to some holders of Celesio’s convertible bonds than it paid to the shareholders of Celesio’s stock, Magnetar Capital Master Fund Ltd. et al. v. Dragonfly GmbH & Co KGaA, No. 3- 05 O 44/14. On December 5, 2014, the court dismissed Magnetar’s lawsuit. Magnetar subsequently appealed that ruling. On January 19, 2016, the appellate court issued a ruling reversing the lower court’s decision. The Company plans to appeal.

From time to time, the Company receives subpoenas or requests for information from various government agencies. The Company generally responds to such subpoenas and requests in a cooperative, thorough and timely manner. These responses sometimes require time and effort and can result in considerable costs being incurred by the Company. Such subpoenas and requests also can lead to the assertion of claims or the commencement of civil or criminal legal proceedings against the Company and other members of the health care industry, as well as to settlements. Examples of such subpoenas and investigations are included in the Company’s 2015 Annual Report on Form 10-K. The Company continues to receive and respond to these requests.

Value Added Tax Assessments

We operate in various countries outside the United States which collect value added taxes (“VAT”). The determination of the manner in which a VAT applies to our foreign operations is subject to varying interpretations arising from the complex nature of the tax laws. We have received assessments for VAT which are in various stages of appeal. We disagree with these assessments and believe that we have strong legal arguments to defend our tax positions. Certain VAT assessments relate to years covered by an indemnification agreement. Due to the complex nature of the tax laws, it is not possible to estimate the outcome of these matters. However, based on the currently available information, we believe the ultimate outcome of these matters will not have a material adverse effect on our financial position, cash flows or results of operations.