XML 134 R116.htm IDEA: XBRL DOCUMENT
v3.22.1

Segments of Business - Narrative (Details) product in Thousands, $ in Millions |  |  | 3 Months Ended | 6 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | --- | ---
Jul. 23, 2021 USD ($) | Mar. 09, 2020 USD ($) | Mar. 31, 2020 USD ($) | Sep. 30, 2019 USD ($) | Jun. 30, 2019 USD ($) | Sep. 30, 2021 segment | Mar. 31, 2021 segment | Mar. 31, 2022 USD ($) country product segment | Mar. 31, 2021 USD ($) | Mar. 31, 2020 USD ($)
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |
Number of reportable segments | segment |  |  |  |  |  | 4 | 4 | 4 |  |
Credits associated with last-in, first-out inventory method |  |  |  |  |  |  |  | $ (23) | $ (38) | $ (252)
Company's International Segment Operating Loss [Abstract] |  |  |  |  |  |  |  |  |  |
Charge for remeasurement to fair value |  |  |  |  |  |  |  | 1,509 | 0 | 0
Goodwill impairment charge |  |  |  |  |  |  |  | 0 | 69 | 2
Equity earnings and charges from investment in Change Healthcare Joint Venture |  |  |  |  |  |  |  | (43) | (48) | (36)
Corporate expenses, net [Abstract] |  |  |  |  |  |  |  |  |  |
Net gains associated with equity investments |  |  |  |  |  |  |  | (98) | (133) |
Corporate expenses, net |  |  |  |  |  |  |  | (1,073) | (8,645) | (973)
Litigation settlement charges |  |  |  |  |  |  |  | 274 | 7,936 | 82
Loss on debt extinguishment |  |  |  |  |  |  |  | 191 | 0 | 0
Tender Offer Notes | Loans payable |  |  |  |  |  |  |  |  |  |
Corporate expenses, net [Abstract] |  |  |  |  |  |  |  |  |  |
Loss on debt extinguishment | $ 191 |  |  |  |  |  |  | $ (191) |  |
German Wholesale Business |  |  |  |  |  |  |  |  |  |
Company's International Segment Operating Loss [Abstract] |  |  |  |  |  |  |  |  |  |
Noncontrolling interest (percent) |  |  |  |  |  |  |  | 30.00% |  |
National Prescription Opiate Litigation |  |  |  |  |  |  |  |  |  |
Corporate expenses, net [Abstract] |  |  |  |  |  |  |  |  |  |
Loss contingency accrual, period increase (decrease) |  |  |  |  |  |  |  | $ 274 | 8,100 |
German Wholesale Business |  |  |  |  |  |  |  |  |  |
Company's International Segment Operating Loss [Abstract] |  |  |  |  |  |  |  |  |  |
Gain from sale of equity method investment |  |  |  |  |  |  |  | 42 |  |
Held-for-sale | U.K. Businesses (Disposal Group) |  |  |  |  |  |  |  |  |  |
Company's International Segment Operating Loss [Abstract] |  |  |  |  |  |  |  |  |  |
Charge for remeasurement to fair value |  |  |  |  |  |  |  | 1,200 |  |
Held-for-sale | E.U. Businesses (Disposal Group) |  |  |  |  |  |  |  |  |  |
Company's International Segment Operating Loss [Abstract] |  |  |  |  |  |  |  |  |  |
Charge for remeasurement to fair value |  |  |  |  |  |  |  | 438 |  |
Corporate | Held-for-sale | U.K. Businesses (Disposal Group) |  |  |  |  |  |  |  |  |  |
Company's International Segment Operating Loss [Abstract] |  |  |  |  |  |  |  |  |  |
Charge for remeasurement to fair value |  |  |  |  |  |  |  | 42 |  |
Corporate | Held-for-sale | E.U. Businesses (Disposal Group) |  |  |  |  |  |  |  |  |  |
Company's International Segment Operating Loss [Abstract] |  |  |  |  |  |  |  |  |  |
Charge for remeasurement to fair value |  |  |  |  |  |  |  | 55 |  |
For Two Counties In re: National Prescription Opiate Litigation |  |  |  |  |  |  |  |  |  |
Corporate expenses, net [Abstract] |  |  |  |  |  |  |  |  |  |
Litigation settlement charges |  |  |  |  |  |  |  |  |  | 82
Shareholder Derivative Action |  |  |  |  |  |  |  |  |  |
Corporate expenses, net [Abstract] |  |  |  |  |  |  |  |  |  |
Corporate expenses, net |  |  |  |  |  |  |  |  | (131) |
Pension Plans, Defined Benefit | U.S. Plans |  |  |  |  |  |  |  |  |  |
Corporate expenses, net [Abstract] |  |  |  |  |  |  |  |  |  |
Pre-tax pension settlement charges |  |  |  | $ 105 | $ 17 |  |  |  |  | 122
Change Healthcare |  |  |  |  |  |  |  |  |  |
Company's International Segment Operating Loss [Abstract] |  |  |  |  |  |  |  |  |  |
Gain from sale of equity method investment |  | $ 414 | $ 414 |  |  |  |  |  |  |
Corporate Joint Venture |  |  |  |  |  |  |  |  |  |
Company's International Segment Operating Loss [Abstract] |  |  |  |  |  |  |  |  |  |
Pre-tax dilution loss |  |  |  | 246 |  |  |  |  |  |
Corporate Joint Venture | Change Healthcare |  |  |  |  |  |  |  |  |  |
Company's International Segment Operating Loss [Abstract] |  |  |  |  |  |  |  |  |  |
Gain from sale of equity method investment |  |  | $ 414 |  |  |  |  |  |  | (414)
Pre-tax other-than-temporary impairment |  |  |  | $ 1,200 |  |  |  |  |  | 1,200
Pre-tax dilution loss |  |  |  |  |  |  |  |  |  | 246
Equity earnings and charges from investment in Change Healthcare Joint Venture |  |  |  |  |  |  |  |  |  | 119
International |  |  |  |  |  |  |  |  |  |
Company's International Segment Operating Loss [Abstract] |  |  |  |  |  |  |  |  |  |
Charge for remeasurement to fair value |  |  |  |  |  |  |  |  | 58 | 275
Goodwill impairment charge |  |  |  |  |  |  |  |  | 69 |
Long-lived asset impairment charges, before tax |  |  |  |  |  |  |  | $ 36 | $ 115 | $ 112
International | Operating Segments |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |
Derived revenues (percent) |  |  |  |  |  |  |  | 8.00% | 8.00% | 8.00%
International | Operating Segments | Disposal Group, Disposed of by Sale, Not Discontinued Operations | Canadian Health Benefit Claims Management and Plan Administrative Services Business |  |  |  |  |  |  |  |  |  |
Company's International Segment Operating Loss [Abstract] |  |  |  |  |  |  |  |  |  |
Pre-tax gain on sale of business |  |  |  |  |  |  |  | $ (59) |  |
International | Operating Segments | Held-for-sale | German Wholesale Business | Walgreens Boots Alliance Joint Venture |  |  |  |  |  |  |  |  |  |
Company's International Segment Operating Loss [Abstract] |  |  |  |  |  |  |  |  |  |
Gain from sale of equity method investment |  |  |  |  |  |  |  | 42 |  |
Charge for remeasurement to fair value |  |  |  |  |  |  |  |  | $ 58 | $ 275
International | Operating Segments | Held-for-sale | U.K. Businesses (Disposal Group) |  |  |  |  |  |  |  |  |  |
Company's International Segment Operating Loss [Abstract] |  |  |  |  |  |  |  |  |  |
Charge for remeasurement to fair value |  |  |  |  |  |  |  | 1,100 |  |
International | Operating Segments | Held-for-sale | E.U. Businesses (Disposal Group) |  |  |  |  |  |  |  |  |  |
Company's International Segment Operating Loss [Abstract] |  |  |  |  |  |  |  |  |  |
Charge for remeasurement to fair value |  |  |  |  |  |  |  | $ 383 |  |
International | Europe |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |
Number of countries in which entity operates | country |  |  |  |  |  |  |  | 11 |  |
U.S. Pharmaceutical |  |  |  |  |  |  |  |  |  |
Company's International Segment Operating Loss [Abstract] |  |  |  |  |  |  |  |  |  |
Goodwill impairment charge |  |  |  |  |  |  |  |  | 0 |
U.S. Pharmaceutical | New York Opioid Tax Surcharge |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |
Charge recorded related to Company's share of the litigation settlement |  |  |  |  |  |  |  |  | $ 50 |
U.S. Pharmaceutical | Operating Segments |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |
Derived revenues (percent) |  |  |  |  |  |  |  | 1.00% | 1.00% | 1.00%
Net cash proceeds from settlements |  |  |  |  |  |  |  | $ (46) | $ (181) | $ (22)
Medical-Surgical Solutions |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |
Number of national brand medical surgical products | product |  |  |  |  |  |  |  | 285 |  |
Inventory write-down charges |  |  |  |  |  |  |  | $ 164 | 136 |
Company's International Segment Operating Loss [Abstract] |  |  |  |  |  |  |  |  |  |
Goodwill impairment charge |  |  |  |  |  |  |  |  | $ 0 |
Medical-Surgical Solutions | Operating Segments |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |
Derived revenues (percent) |  |  |  |  |  |  |  | 3.00% | 3.00% | 3.00%
Prescription Technology Solutions | Operating Segments |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |
Derived revenues (percent) |  |  |  |  |  |  |  | 40.00% | 40.00% | 40.00%

X
- Definition Corporate Operating Expense and Other Income, Net + References No definition available. + Details
Name: | mck_CorporateOperatingExpenseandOtherIncomeNet
Namespace Prefix: | mck_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Number of National Brand Medical Surgical Products + References No definition available. + Details
Name: | mck_NumberOfNationalBrandMedicalSurgicalProducts
Namespace Prefix: | mck_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Revenue Derived From Services, Percentage + References No definition available. + Details
Name: | mck_RevenueDerivedFromServicesPercentage
Namespace Prefix: | mck_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=123351718&loc=d3e2420-110228 + Details
Name: | us-gaap_AssetImpairmentCharges
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of unrealized gain (loss) recognized in earnings from investment in debt and equity securities measured at fair value with change in fair value recognized in net income, and recognized from transfer of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) and investment in debt security measured at amortized cost (held-to-maturity) to investment in debt security measured at fair value with change in fair value recognized in net income (trading). Excludes other-than-temporary impairment (OTTI). + References No definition available. + Details
Name: | us-gaap_DebtAndEquitySecuritiesUnrealizedGainLossExcludingOtherThanTemporaryImpairment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk related to obligation and assets used to effect settlement. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(7) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 3A -URI http://asc.fasb.org/extlink&oid=123453770&loc=SL108413299-114919 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(7) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e2709-114920 + Details
Name: | us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlements1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount, before tax, of (gain) loss recognized for the (reversal of write-down) write-down to fair value, less cost to sell, of a disposal group. Excludes discontinued operations. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2941-110230 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=123351718&loc=d3e2443-110228 + Details
Name: | us-gaap_DisposalGroupNotDiscontinuedOperationLossGainOnWriteDown
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition This item represents an other than temporary decline in value that has been recognized against an investment accounted for under the equity method of accounting. The excess of the carrying amount over the fair value of the investment represents the amount of the write down which is or was reflected in earnings. The written down value is a new cost basis with the adjusted value of the investment becoming its new carrying value subject to the equity accounting method. Evidence of a loss in value might include, but would not necessarily be limited to, absence of an ability to recover the carrying amount of the investment or inability of the investee to sustain an earnings capacity which would justify the carrying amount of the investment. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 35 -Paragraph 32 -URI http://asc.fasb.org/extlink&oid=124268079&loc=d3e32787-111569 + Details
Name: | us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of gain (loss) on sale or disposal of an equity method investment. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(b)(7)(c)) -URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(b)(9)(a)) -URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227 + Details
Name: | us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of gain (loss) from sale and disposal of integrated set of activities and assets capable of being conducted and managed for purpose of providing return in form of dividend, lower cost, or other economic benefit to investor, owner, member and participant. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 1B -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109239629&loc=SL4582445-111684 + Details
Name: | us-gaap_GainLossOnSaleOfBusiness
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of gain (loss) on sale or disposal of equity in securities of subsidiaries or equity method investee. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(b)(9)(a)) -URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(13)(g)) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(b)(7)(c)) -URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227 Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(3)(a)) -URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 + Details
Name: | us-gaap_GainLossOnSaleOfStockInSubsidiaryOrEquityMethodInvestee
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of gain (loss) recognized in settlement of litigation and insurance claims. Excludes claims within an insurance entity's normal claims settlement process. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349 + Details
Name: | us-gaap_GainLossRelatedToLitigationSettlement
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 50 -Section 40 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=123467658&loc=d3e12355-112629 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 50 -Section 40 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=123467658&loc=d3e12317-112629 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585 + Details
Name: | us-gaap_GainsLossesOnExtinguishmentOfDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121556970&loc=d3e13854-109267 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13777-109266 + Details
Name: | us-gaap_GoodwillImpairmentLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of income (loss) for proportionate share of equity method investee's income (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(12)) -URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(10)) -URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(13)(f)) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8736-108599 Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=109237563&loc=d3e33749-111570 + Details
Name: | us-gaap_IncomeLossFromEquityMethodInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The change in the inventory reserve representing the cumulative difference in cost between the first in, first out and the last in, first out inventory valuation methods, which change has been reflected in the statement of income during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.6b) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.6c) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.6a) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 330 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 5.L) -URI http://asc.fasb.org/extlink&oid=27011343&loc=d3e99989-122729 + Details
Name: | us-gaap_InventoryLIFOReservePeriodCharge
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of loss from reductions in inventory due to subsequent measurement adjustments, including, but not limited to, physical deterioration, obsolescence, or changes in price levels. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 330 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=116847112&loc=d3e4542-108314 + Details
Name: | us-gaap_InventoryWriteDown
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of increase (decrease) in loss contingency liability. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349 + Details
Name: | us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount charged against operating income increasing loss contingency liability, after adjustments to reduce previously estimated charges. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349 + Details
Name: | us-gaap_LossContingencyAccrualProvision
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity. + References No definition available. + Details
Name: | us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of countries in which the entity operates as of balance sheet date. + References No definition available. + Details
Name: | us-gaap_NumberOfCountriesInWhichEntityOperates
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8672-108599 + Details
Name: | us-gaap_NumberOfReportableSegments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Cash received for the settlement of litigation during the current period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 25 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3536-108585 + Details
Name: | us-gaap_ProceedsFromLegalSettlements
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_SegmentReportingInformationAdditionalInformationAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_SegmentReportingInformationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_SegmentReportingInformationProfitLossAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_DebtInstrumentAxis=mck_TenderOfferNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_LoansPayableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_OwnershipAxis=mck_GermanWholesaleBusinessMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LossContingenciesByNatureOfContingencyAxis=mck_NationalPrescriptionOpiateLitigationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=mck_GermanWholesaleBusinessMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DisposalGroupClassificationAxis=us-gaap_DisposalGroupHeldforsaleNotDiscontinuedOperationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=mck_UKBusinessesDisposalGroupMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=mck_EUBusinessesDisposalGroupMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ConsolidationItemsAxis=us-gaap_CorporateNonSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_LitigationCaseAxis=mck_ForTwoCountiesInreNationalPrescriptionOpiateLitigationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_LitigationCaseAxis=mck_ShareholderDerivativeActionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_RetirementPlanSponsorLocationAxis=country_US
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=mck_ChangeHealthcareLLCChangeHealthcareMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_CorporateJointVentureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=mck_InternationalSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ConsolidationItemsAxis=us-gaap_OperatingSegmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DisposalGroupClassificationAxis=us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=mck_CanadianHealthBenefitClaimsManagementAndPlanAdministrativeServicesBusinessMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_OwnershipAxis=mck_WalgreensBootsAllianceJointVentureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=srt_EuropeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=mck_USPharmaceuticalSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LossContingenciesByNatureOfContingencyAxis=mck_NewYorkOpioidTaxSurchargeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=mck_MedicalSurgicalSolutionsSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=mck_PrescriptionTechnologySolutionsSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |