Disposal Group, Including Discontinued Operation, Long-term Debt, Current Maturities

No definition available.

Name:	mck_DisposalGroupIncludingDiscontinuedOperationLongTermDebtCurrentMaturities
Namespace Prefix:	mck_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Disposal Group, Including Discontinued Operation, Long-term Debt, Excluding Current Maturities

+ References

No definition available.

+ Details

Name:	mck_DisposalGroupIncludingDiscontinuedOperationLongTermDebtExcludingCurrentMaturities
Namespace Prefix:	mck_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of short-term and long-term debt and lease obligation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13,16)
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

+ Details

Name:	us-gaap_DebtAndCapitalLeaseObligations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

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 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

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

- Definition

Present value of lessee's discounted obligation for lease payments from finance lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918701-209980

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918627-209977

+ Details

Name:	us-gaap_FinanceLeaseLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=123466204&loc=SL6031897-161870

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69C
-URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69B
-URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1D
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495340-112611

Reference 7: 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(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_LongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of long-term debt and lease obligation, classified as noncurrent.

+ 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(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_LongTermDebtAndCapitalLeaseObligations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of long-term debt and lease obligation, classified as current.

+ 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 210.5-02.20)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Debt and Financing Activities - Schedule of Long-Term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2021	Aug. 12, 2021	Jul. 23, 2021	Jul. 17, 2021	Mar. 31, 2021
Debt Instrument [Line Items]
Lease and other obligation	$ 251				$ 270
Total debt	5,985				7,148
Less: Current portion	39				742
Total long-term debt	5,946				6,406
Held-for-sale \| European Businesses (Disposal Group)
Debt Instrument [Line Items]
Current portion of long-term debt	4
Long-term debt	$ 15
2.70% Notes due December 15, 2022 \| Notes payable
Debt Instrument [Line Items]
Interest rate on debt instrument (percent)	2.70%
Debt outstanding	$ 400				400
2.85% Notes due March 15, 2023 \| Notes payable
Debt Instrument [Line Items]
Interest rate on debt instrument (percent)	2.85%		2.85%
Debt outstanding	$ 360				400
3.80% Notes due March 15, 2024 \| Notes payable
Debt Instrument [Line Items]
Interest rate on debt instrument (percent)	3.80%		3.80%
Debt outstanding	$ 918				1,100
0.90% Notes due December 3, 2025 \| Notes payable
Debt Instrument [Line Items]
Interest rate on debt instrument (percent)	0.90%
Debt outstanding	$ 500				500
1.30% Notes due August 15, 2026 \| Notes payable
Debt Instrument [Line Items]
Interest rate on debt instrument (percent)	1.30%	1.30%
Debt outstanding	$ 498				0
7.65% Debentures due March 1, 2027 \| Notes payable
Debt Instrument [Line Items]
Interest rate on debt instrument (percent)	7.65%		7.65%
Debt outstanding	$ 150				167
3.95% Notes due February 16, 2028 \| Notes payable
Debt Instrument [Line Items]
Interest rate on debt instrument (percent)	3.95%		3.95%
Debt outstanding	$ 343				600
4.75% Notes due May 30, 2029 \| Notes payable
Debt Instrument [Line Items]
Interest rate on debt instrument (percent)	4.75%		4.75%
Debt outstanding	$ 197				400
6.00% Notes due March 1, 2041 \| Notes payable
Debt Instrument [Line Items]
Interest rate on debt instrument (percent)	6.00%		6.00%
Debt outstanding	$ 220				282
4.88% Notes due March 15, 2044 \| Notes payable
Debt Instrument [Line Items]
Interest rate on debt instrument (percent)	4.88%		4.88%
Debt outstanding	$ 255				411
0.63% Euro Notes due August 17, 2021 \| Notes payable
Debt Instrument [Line Items]
Interest rate on debt instrument (percent)	0.63%			0.63%
Debt outstanding	$ 0				704
1.50% Euro Notes due November 17, 2025 \| Notes payable
Debt Instrument [Line Items]
Interest rate on debt instrument (percent)	1.50%
Debt outstanding	$ 703				700
1.63% Euro Notes due October 30, 2026 \| Notes payable
Debt Instrument [Line Items]
Interest rate on debt instrument (percent)	1.63%
Debt outstanding	$ 588				587
3.13% Sterling Notes due February 17, 2029 \| Notes payable
Debt Instrument [Line Items]
Interest rate on debt instrument (percent)	3.13%
Debt outstanding	$ 602				$ 627