XML 110 R121.htm IDEA: XBRL DOCUMENT
v3.20.1

Stockholders' Equity - Narrative (Details) |  |  | 1 Months Ended | 3 Months Ended | 8 Months Ended | 10 Months Ended | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Mar. 09, 2020 shares | Jun. 30, 2019 $ / shares | Jul. 31, 2019 $ / shares | Dec. 31, 2018 USD ($) $ / shares shares | Mar. 31, 2018 USD ($) shares | Aug. 31, 2017 USD ($) | Jun. 30, 2017 USD ($) | Jun. 30, 2018 $ / shares shares | Mar. 31, 2018 USD ($) shares | Mar. 31, 2018 USD ($) shares | Mar. 31, 2020 USD ($) vote $ / shares shares | Mar. 31, 2019 USD ($) $ / shares shares | Mar. 31, 2018 USD ($) $ / shares shares | Mar. 10, 2020 $ / shares shares | May 31, 2018 USD ($) | Mar. 31, 2017 USD ($)
Dividends Payable [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of votes | vote |  |  |  |  |  |  |  |  |  |  | 1 |  |  |  |  |
Cash dividends declared per common share (in dollars per share) | $ / shares |  | $ 0.39 | $ 0.41 |  |  |  |  |  |  |  | $ 1.62 | $ 1.51 | $ 1.30 |  |  |
Average price paid per share (in dollars per share) | $ / shares |  |  |  |  |  |  |  | $ 143.66 |  |  | $ 138.94 | $ 130.72 | $ 151.06 |  |  |
Shares repurchased |  |  |  |  |  |  |  |  |  |  | $ 1,934,000,000 | $ 1,627,000,000 | $ 1,650,000,000 |  |  |
Shares repurchased (in shares) | shares |  |  |  |  |  |  |  |  |  |  | 13,900,000 | 13,500,000 | 10,500,000 |  |  |
Total authorization outstanding for repurchases of common stock |  |  |  |  | $ 1,096,000,000 |  |  |  | $ 1,096,000,000 | $ 1,096,000,000 | $ 1,535,000,000 | $ 3,469,000,000 | $ 1,096,000,000 |  |  | $ 2,746,000,000
Additional authorized |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 4,000,000,000 |
Repurchase of common stock |  |  |  |  |  |  |  |  |  |  | $ 1,934,000,000 | $ 1,627,000,000 | 1,650,000,000 |  |  |
Treasury stock retired (in shares) | shares | 15,400,000 |  |  |  |  |  |  |  |  |  |  | 5,000,000.0 |  |  |  |
Retirement of common stock |  |  |  |  |  |  |  |  |  |  |  | $ 542,000,000 |  |  |  |
Shares distributed to stockholders (shares) | shares | 176,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, par value (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  |  | $ 0.01 | $ 0.01 |  |  |  |
Other comprehensive income (loss) before reclassifications |  |  |  |  |  |  |  |  |  |  | $ 53,000,000 | $ (207,000,000) |  |  |  |
Net foreign currency translation gains (losses) |  |  |  |  |  |  |  |  |  |  | 149,000,000 | (198,000,000) | 609,000,000 |  |  |
Gains (losses) from net investment hedges |  |  |  |  |  |  |  |  |  |  | 39,000,000 | 259,000,000 | (268,000,000) |  |  |
Retained Earnings |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividends Payable [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Retirement of common stock |  |  |  |  |  |  |  |  |  |  |  | 472,000,000 |  |  |  |
Additional Paid-in Capital |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividends Payable [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Repurchase of common stock |  |  |  |  |  |  |  |  |  |  | 0 | (150,000,000) | 36,000,000 |  |  |
Retirement of common stock |  |  |  |  |  |  |  |  |  |  |  | 70,000,000 |  |  |  |
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividends Payable [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other comprehensive income (loss) before reclassifications |  |  |  |  |  |  |  |  |  |  | (151,000,000) | (431,000,000) | 804,000,000 |  |  |
Net foreign currency translation gains (losses) |  |  |  |  |  |  |  |  |  |  | (151,000,000) | (431,000,000) | 804,000,000 |  |  |
Accumulated Foreign Currency Adjustment Attributable to Noncontrolling Interest |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividends Payable [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net foreign currency translation gains (losses) |  |  |  |  |  |  |  |  |  |  | 1,000,000 | (61,000,000) | 189,000,000 |  |  |
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Including Portion Attributable to Noncontrolling Interest |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividends Payable [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other comprehensive income (loss) before reclassifications |  |  |  |  |  |  |  |  |  |  | $ 2,000,000 | $ (5,000,000) | $ (4,000,000) |  |  |
Open Market Transactions |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividends Payable [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Repurchase of common stock (in shares) | shares |  |  |  |  |  |  |  |  |  |  |  |  | 3,500,000 |  |  |
Average price paid per share (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  |  | $ 144.68 |  | $ 144.43 |  |  |
Repurchase of common stock |  |  |  |  |  |  |  |  |  |  |  |  | $ 500,000,000 |  |  |
Accelerated Share Repurchase |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividends Payable [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Average price paid per share (in dollars per share) | $ / shares |  |  |  | $ 117.98 |  |  |  |  |  |  | $ 127.68 |  |  |  |  |
Shares repurchased |  |  |  |  | $ 500,000,000 | $ 400,000,000 | $ 250,000,000 |  |  |  |  |  |  |  |  |
Shares repurchased (in shares) | shares |  |  |  | 2,100,000 |  |  |  |  |  |  | 4,700,000 |  |  |  |  |
Additional authorized |  |  |  | $ 250,000,000 |  |  |  |  |  |  | $ 600,000,000 |  |  |  |  |
June 2017 Accelerated Share Repurchase |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividends Payable [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares repurchased (in shares) | shares |  |  |  |  |  |  |  |  |  | 1,500,000 |  |  |  |  |  |
August 2017 Accelerated Share Repurchase |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividends Payable [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares repurchased (in shares) | shares |  |  |  |  |  |  |  |  | 2,700,000 |  |  |  |  |  |  |
March 2018 ASR Program |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividends Payable [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares repurchased (in shares) | shares |  |  |  |  | 2,500,000 |  |  | 1,000,000.0 |  |  |  |  |  |  |  |
May 2018 Share Repurchase Program |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividends Payable [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Average price paid per share (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  |  |  | $ 132.14 |  |  |  |
Shares repurchased |  |  |  |  |  |  |  |  |  |  | $ 1,300,000,000 | $ 1,400,000,000 |  |  |  |
Shares repurchased (in shares) | shares |  |  |  |  |  |  |  |  |  |  | 9,200,000 | 10,400,000 |  |  |  |
Total authorization outstanding for repurchases of common stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5,100,000,000 |
Additional authorized |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 4,000,000,000.0 |
Net Investment Hedging |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividends Payable [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gains (losses) recorded in other comprehensive income |  |  |  |  |  |  |  |  |  |  | $ 76,000,000 | $ 53,000,000 | $ (7,000,000) |  |  |
Separation of Change Healthcare JV |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividends Payable [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares distributed to stockholders (shares) | shares | 176,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares converted into per share converted (shares) | shares |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 |  |
Common stock, par value (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 0.001 |  |

X
- Definition Common Stock, Conversion Basis, Number of Shares Issued For Each Share Converted + References No definition available. + Details
Name: | mck_CommonStockConversionBasisNumberofSharesIssuedForEachShareConverted
Namespace Prefix: | mck_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Common Stock, Voting Rights, Number of Votes Per Common Share + References No definition available. + Details
Name: | mck_CommonStockVotingRightsNumberofVotesPerCommonShare
Namespace Prefix: | mck_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Exchange Offer, Shares Distributed + References No definition available. + Details
Name: | mck_ExchangeOfferSharesDistributed
Namespace Prefix: | mck_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Aggregate dividends declared during the period for each share of common stock outstanding. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
Name: | us-gaap_CommonStockDividendsPerShareDeclared
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Face amount or stated value per share of common stock. + 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(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_CommonStockParOrStatedValuePerShare
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

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_DividendsPayableLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount after tax, before reclassification adjustments of other comprehensive income (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669686-108580 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 55 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=118951672&loc=d3e1436-108581 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount after tax and reclassification adjustments of other comprehensive income (loss). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669619-108580 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 55 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=118951672&loc=d3e1436-108581 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1B -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669625-108580 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of stock repurchase plan authorized. + References No definition available. + Details
Name: | us-gaap_StockRepurchaseProgramAuthorizedAmount1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount remaining of a stock repurchase plan authorized. + References No definition available. + Details
Name: | us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 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(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 4: 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(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_StockRepurchasedDuringPeriodShares
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock. + 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(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 4: 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(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_StockRepurchasedDuringPeriodValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount, before tax, of increase (decrease) in the cumulative translation adjustment from gain (loss) on foreign currency derivatives that are designated as, and are effective as, economic hedges of a net investment in a foreign entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 30 -Section 45 -Paragraph 20 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118261656&loc=d3e32211-110900 + Details
Name: | us-gaap_TranslationAdjustmentForNetInvestmentHedgeIncreaseDecreaseGrossOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount, after tax, of reclassification from accumulated other comprehensive income (AOCI) of gain (loss) from increase (decrease) in fair value of net investment hedge. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4CCC -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109998896-113959 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669646-108580 + Details
Name: | us-gaap_TranslationAdjustmentForNetInvestmentHedgeIncreaseDecreaseNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Total cost of shares repurchased divided by the total number of shares repurchased. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655 + Details
Name: | us-gaap_TreasuryStockAcquiredAverageCostPerShare
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of decrease of par value, additional paid in capital (APIC) and retained earnings of common and preferred stock retired from treasury when treasury stock is accounted for under the par value method. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 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(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
Name: | us-gaap_TreasuryStockRetiredParValueMethodAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Number of shares that have been repurchased during the period and are being held in treasury. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 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(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_TreasuryStockSharesAcquired
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of shares of common and preferred stock retired from treasury during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 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(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 + Details
Name: | us-gaap_TreasuryStockSharesRetired
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
Name: | us-gaap_TreasuryStockValueAcquiredCostMethod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_RetainedEarningsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AdditionalPaidInCapitalMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedForeignCurrencyAdjustmentAttributableToNoncontrollingInterestMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetGainLossAttributableToNoncontrollingInterestMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareRepurchaseProgramAxis=mck_OpenMarketTransactionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareRepurchaseProgramAxis=mck_AcceleratedShareRepurchaseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareRepurchaseProgramAxis=mck_June2017AcceleratedShareRepurchaseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareRepurchaseProgramAxis=mck_August2017AcceleratedShareRepurchaseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareRepurchaseProgramAxis=mck_March2018ASRProgramMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareRepurchaseProgramAxis=mck_May2018ShareRepurchaseProgramMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_NetInvestmentHedgingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConversionOfStockByUniqueDescriptionAxis=mck_SeparationofChangeHealthcareJVMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |