XML 63 R100.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Pension Benefits (Narrative) (Details) (USD $) | 1 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 1996 | Mar. 31, 2015 | Mar. 31, 2014 | Mar. 31, 2013
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |
Expected amortization of prior service cost (credit) in 2016 |  | $ (1,000,000)us-gaap_DefinedBenefitPlanFutureAmortizationOfPriorServiceCostCredit |  |  |  |  |
Expected amortization of actuarial gain (loss) in 2016 |  | (47,000,000)us-gaap_DefinedBenefitPlanFutureAmortizationOfGainLoss |  |  |  |  |
Prior service (cost) credit |  | 7,000,000us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax |  |  |  |  |
Amortization of Net actuarial loss |  | (31,000,000)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax |  |  |  |  |
Expected Benefit Payments in 2016 |  | 74,000,000us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths |  |  |  |  |
Expected Benefit Payments in 2017 |  | 172,000,000us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo |  |  |  |  |
Expected Benefit Payments in 2018 |  | 75,000,000us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree |  |  |  |  |
Expected Benefit Payments in 2019 |  | 94,000,000us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour |  |  |  |  |
Expected Benefit Payments in 2020 |  | 66,000,000us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive |  |  |  |  |
Expected Benefit Payments, 2021 through 2025 |  | 333,000,000us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter |  |  |  |  |
Expected contributions in next fiscal year |  | 54,000,000us-gaap_DefinedBenefitPlansEstimatedFutureEmployerContributionsInNextFiscalYear |  |  |  |  |
Discount Rate, Defined Benefit Liability, Change in Basis Points |  | (40)mck_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationChangeInRateBasisPoints |  |  |  |  |
United States Defined Contribution Pension [Member] |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |
Contributions to PSIP |  | 75.00%us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent / us-gaap_DefinedContributionPlanTypeAxis = mck_UnitedStatesDefinedContributionPensionMember |  |  |  |  |
Defined Contribution Plan, PSIP Expense and Other |  | 103,000,000us-gaap_DefinedContributionPlanCostRecognized / us-gaap_DefinedContributionPlanTypeAxis = mck_UnitedStatesDefinedContributionPensionMember |  | 83,000,000us-gaap_DefinedContributionPlanCostRecognized / us-gaap_DefinedContributionPlanTypeAxis = mck_UnitedStatesDefinedContributionPensionMember |  | 65,000,000us-gaap_DefinedContributionPlanCostRecognized / us-gaap_DefinedContributionPlanTypeAxis = mck_UnitedStatesDefinedContributionPensionMember |
Pension Plans, Defined Benefit [Member] |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |
Unit Value Of Cash And Cash Equivalents |  | $ 1.00mck_UnitValueOfCashAndCashEquivalents / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember |  |  |  |  |
Norwegian Public Service Pension Fund (SPK) [Member] |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |
Defined Benefit Plan, Plans Obligations In Excess Of Plan Asset Shortfall Percent |  | 1.00%mck_DefinedBenefitPlanPlansObligationsInExcessOfPlanAssetShortfallPercent / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = mck_NorwegianPublicServicePensionFundSPKMember |  |  |  |  |
Defined Benefit Plan, Plans Obligations In Excess Of Plan Asset Shortfall Remedy Period |  | 2 years |  |  |  |  |
Pension And Other Postretirement Defined Benefit Plans, Plan Asset Value |  | 39,000,000mck_PensionAndOtherPostretirementDefinedBenefitPlansPlanAssetValue / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = mck_NorwegianPublicServicePensionFundSPKMember |  |  |  |  |
United States [Member] |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |
Defined Benefit, Plan Highest Average Pay Months | 60 months |  |  |  |  |  |
Defined Benefit, Plan Years Prior To Freeze Date | 15 years |  |  |  |  |  |
Defined Benefit Plan, Actuarial Losses, Percentage Exceeding Greater Of Projected Benefit Obligation Or Market Value of Assets |  | 10.00%mck_DefinedBenefitPlanActuarialLossesPercentageExceedingGreaterOfProjectedBenefitObligationOrMarketValueOfAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember |  |  |  |  |
Prior service (cost) credit |  | 8,000,000us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember |  | 0us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember |  | (1,000,000)us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember |
Amortization of Net actuarial loss |  | (27,000,000)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember |  | (32,000,000)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember |  | (27,000,000)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember |
Projected benefit obligation |  | 583,000,000us-gaap_DefinedBenefitPlanBenefitObligation / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember | [1] | 540,000,000us-gaap_DefinedBenefitPlanBenefitObligation / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember | [1] | 580,000,000us-gaap_DefinedBenefitPlanBenefitObligation / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember | [1]
Discount Rates |  | 3.18%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember |  | 3.58%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember |  |  |
United States [Member] | Equity Securities [Member] |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |
Target Plan Asset Allocations |  | 50.00%us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember |  | 50.00%us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember |  |  |
United States [Member] | Fixed Income Investments [Member] |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |
Target Plan Asset Allocations |  | 45.00%us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_FixedIncomeInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember |  | 45.00%us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_FixedIncomeInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember |  |  |
United States [Member] | Other Investments [Member] |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |
Target Plan Asset Allocations |  | 5.00%us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_OtherInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember |  | 5.00%us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_OtherInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember |  |  |
Foreign Pension Plan, Defined Benefit [Member] |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |
Prior service (cost) credit |  | 2,000,000us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember |  | 2,000,000us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember |  | 0us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember |
Amortization of Net actuarial loss |  | (5,000,000)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember |  | (4,000,000)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember |  | (4,000,000)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember |
Projected benefit obligation |  | 963,000,000us-gaap_DefinedBenefitPlanBenefitObligation / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember | [1] | 934,000,000us-gaap_DefinedBenefitPlanBenefitObligation / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember | [1] | 156,000,000us-gaap_DefinedBenefitPlanBenefitObligation / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember | [1]
Discount Rates |  | 2.50%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember |  | 3.92%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember |  |  |
Discount Rate, Defined Benefit Liability, Change in Basis Points |  | (142)mck_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationChangeInRateBasisPoints / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember |  |  |  |  |
Pensjonsordningen for Apoteketaten (POA) [Member] |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |
Defined Benefit Plan, Employer Contributions Percent Exceed Plan Asset |  | 5.00%mck_DefinedBenefitPlanEmployerContributionsPercentExceedPlanAsset / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = mck_PensjonsordningenforApoteketatenPOAMember |  |  |  |  |
Defined Benefit Plan, Contributions by Employer |  | 24,000,000us-gaap_DefinedBenefitPlanContributionsByEmployer / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = mck_PensjonsordningenforApoteketatenPOAMember |  | 5,000,000us-gaap_DefinedBenefitPlanContributionsByEmployer / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = mck_PensjonsordningenforApoteketatenPOAMember |  |  |
Multiemployer Plans, Funded Status |  | 65.00%mck_MulitemployerPlanFundedStatusPercentage / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = mck_PensjonsordningenforApoteketatenPOAMember |  |  |  |  |
Multiemployer Plans, Withdrawal Obligation |  | 0us-gaap_MultiemployerPlansWithdrawalObligation / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = mck_PensjonsordningenforApoteketatenPOAMember |  |  |  |  |
Unfunded plan [Member] | United States [Member] |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |
Projected benefit obligation |  | 189,000,000us-gaap_DefinedBenefitPlanBenefitObligation / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_MultiemployerPlanTypeAxis = mck_UnfundedplanMember |  | 188,000,000us-gaap_DefinedBenefitPlanBenefitObligation / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_MultiemployerPlanTypeAxis = mck_UnfundedplanMember |  |  |
Unfunded plan [Member] | Foreign Pension Plan, Defined Benefit [Member] |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |
Projected benefit obligation |  | $ 222,000,000us-gaap_DefinedBenefitPlanBenefitObligation / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_MultiemployerPlanTypeAxis = mck_UnfundedplanMember |  | $ 260,000,000us-gaap_DefinedBenefitPlanBenefitObligation / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_MultiemployerPlanTypeAxis = mck_UnfundedplanMember |  |  |
Second Part Of Pay Contribution [Member] | United States Defined Contribution Pension [Member] |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |
Company Match Employee Contributions |  | 50.00%us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent / mck_DefinedContributionPlanMatchingAxis = mck_SecondPartOfPayContributionMember / us-gaap_DefinedContributionPlanTypeAxis = mck_UnitedStatesDefinedContributionPensionMember |  |  |  |  |
Employee Contributions |  | 2.00%mck_EmployeeContributions / mck_DefinedContributionPlanMatchingAxis = mck_SecondPartOfPayContributionMember / us-gaap_DefinedContributionPlanTypeAxis = mck_UnitedStatesDefinedContributionPensionMember |  |  |  |  |
First Part Of Pay Contribution [Member] | United States Defined Contribution Pension [Member] |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |
Company Match Employee Contributions |  | 100.00%us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent / mck_DefinedContributionPlanMatchingAxis = mck_FirstPartOfPayContributionMember / us-gaap_DefinedContributionPlanTypeAxis = mck_UnitedStatesDefinedContributionPensionMember |  |  |  |  |
Employee Contributions |  | 3.00%mck_EmployeeContributions / mck_DefinedContributionPlanMatchingAxis = mck_FirstPartOfPayContributionMember / us-gaap_DefinedContributionPlanTypeAxis = mck_UnitedStatesDefinedContributionPensionMember |  |  |  |  |
[1] | The benefit obligation is the projected benefit obligation.

X
- Definition Unrecognized actuarial losses exceeding 10% of the greater of the projected benefit obligation or the market value of assets are amortized straight-line over the average remaining future service periods. + References No definition available. + Details
Name: | mck_DefinedBenefitPlanActuarialLossesPercentageExceedingGreaterOfProjectedBenefitObligationOrMarketValueOfAssets
Namespace Prefix: | mck_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost Rate Of Compensation, Change In Rate, Basis Points + References No definition available. + Details
Name: | mck_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationChangeInRateBasisPoints
Namespace Prefix: | mck_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Defined Benefit Plan, Employer Contributions Percent Exceed Plan Asset + References No definition available. + Details
Name: | mck_DefinedBenefitPlanEmployerContributionsPercentExceedPlanAsset
Namespace Prefix: | mck_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Benefits for the defined benefit retirement plan are based primarily on age of employees at date of retirement, years of creditable service and the average of the highest 60 months of pay during the 15 years prior to the plan freeze date. + References No definition available. + Details
Name: | mck_DefinedBenefitPlanHighestAveragePayMonths
Namespace Prefix: | mck_
Data Type: | us-types:durationStringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Defined Benefit Plan, Plans Obligations In Excess Of Plan Asset Shortfall Percent + References No definition available. + Details
Name: | mck_DefinedBenefitPlanPlansObligationsInExcessOfPlanAssetShortfallPercent
Namespace Prefix: | mck_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Defined Benefit Plan, Plans Obligations In Excess Of Plan Asset Shortfall Remedy Period + References No definition available. + Details
Name: | mck_DefinedBenefitPlanPlansObligationsInExcessOfPlanAssetShortfallRemedyPeriod
Namespace Prefix: | mck_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Benefits for the defined benefit retirement plan are based primarily on age of employees at date of retirement, years of creditable service and the average of the highest 60 months of pay during the 15 years prior to the plan freeze date. + References No definition available. + Details
Name: | mck_DefinedBenefitPlanYearsPriorToFreezeDate
Namespace Prefix: | mck_
Data Type: | us-types:durationStringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of contributions made by plan participants. This item represents a periodic increase to the plan obligation and a percentage increase to plan assets. + References No definition available. + Details
Name: | mck_EmployeeContributions
Namespace Prefix: | mck_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Mulitemployer Plan, Funded Status, Percentage + References No definition available. + Details
Name: | mck_MulitemployerPlanFundedStatusPercentage
Namespace Prefix: | mck_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Pension And Other Postretirement Defined Benefit Plans, Plan Asset Value + References No definition available. + Details
Name: | mck_PensionAndOtherPostretirementDefinedBenefitPlansPlanAssetValue
Namespace Prefix: | mck_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Unit value of cash and cash equivalents + References No definition available. + Details
Name: | mck_UnitValueOfCashAndCashEquivalents
Namespace Prefix: | mck_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition The interest rate used to adjust for the time value of money for the plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition 1) For defined benefit pension plans, the benefit obligation is the projected benefit obligation, which is the actuarial present value as of a date of all benefits attributed by the pension benefit formula to employee service rendered prior to that date. 2) For other postretirement defined benefit plans, the benefit obligation is the accumulated postretirement benefit obligation, which is the actuarial present value of benefits attributed to employee service rendered to a particular date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Projected Benefit Obligation -URI http://asc.fasb.org/extlink&oid=6522206 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Accumulated Postretirement Benefit Obligation -URI http://asc.fasb.org/extlink&oid=6503904 + Details
Name: | us-gaap_DefinedBenefitPlanBenefitObligation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The increase in the fair value of plan assets from contributions made by the employer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanContributionsByEmployer
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of benefits from a defined benefit plan expected to be paid in the five fiscal years after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of benefits from a defined benefit plan expected to be paid in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of benefits from a defined benefit plan expected to be paid in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of benefits from a defined benefit plan expected to be paid in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of benefits from a defined benefit plan expected to be paid in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of benefits from a defined benefit plan expected to be paid in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount included in accumulated other comprehensive income (AOCI) related to gain (loss) expected to be recognized as components of net periodic benefit cost for the fiscal year that follows the most recent annual statement of financial position. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanFutureAmortizationOfGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount included in accumulated other comprehensive income (AOCI) related to prior service cost (credit) expected to be recognized as components of net periodic benefit cost for the fiscal year that follows the most recent annual statement of financial position. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanFutureAmortizationOfPriorServiceCostCredit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of employer's best estimate of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest statement of financial position. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlansEstimatedFutureEmployerContributionsInNextFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Target allocation of investments of this type to total plan assets presented on a weighted average basis. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(i) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (c)(i) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e2446-114920 + Details
Name: | us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of the cost recognized during the period for defined contribution plans. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942 + Details
Name: | us-gaap_DefinedContributionPlanCostRecognized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of the obligation recognized by withdrawing from a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers. + References No definition available. + Details
Name: | us-gaap_MultiemployerPlansWithdrawalObligation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount before tax of reclassification adjustment from accumulated other comprehensive (income) loss for prior service cost (credit) related to pension and other postretirement benefit plans. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=36458714&loc=d3e637-108580 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (j) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (j) -URI http://asc.fasb.org/extlink&oid=36458714&loc=SL7669646-108580 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount before tax of reclassification adjustment from accumulated other comprehensive income (loss) for actuarial gain (loss) related to pension and other postretirement benefit plans. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=36458714&loc=d3e637-108580 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=36458714&loc=d3e689-108580 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (j) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | mck_DefinedContributionPlanMatchingAxis=mck_FirstPartOfPayContributionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | mck_DefinedContributionPlanMatchingAxis=mck_SecondPartOfPayContributionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=mck_NorwegianPublicServicePensionFundSPKMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=mck_PensjonsordningenforApoteketatenPOAMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_ForeignPensionPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedContributionPlanTypeAxis=mck_UnitedStatesDefinedContributionPensionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MultiemployerPlanTypeAxis=mck_UnfundedplanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |