Business Combination, Consolidation Percent

No definition available.

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- Definition

Capitalized Software Held for Internal Use, Useful Life

+ References

No definition available.

+ Details

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- Definition

Capitalized Software Held for Sale, Useful Life

+ References

No definition available.

+ Details

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- Definition

Inventory, LIFO to Market Adjustment

+ References

No definition available.

+ Details

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Balance Type:	debit
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- Details

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Period Type:	duration

- Definition

Supplier reserves

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Tax Recognized, Percent Likely Being Realized

+ References

No definition available.

+ Details

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- Definition

For each balance sheet presented, the amount of accumulated amortization for capitalized computer software costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 985

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

+ Details

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- Definition

The carrying amount of capitalized computer software costs net of accumulated amortization as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 985

-SubTopic 20

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128487-111756

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 985

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756

+ Details

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- Definition

Description of risks that arise due to the volume of business transacted with a particular customer. At a minimum, the description informs financial statement users of the general nature of the risk, but excludes "Information about Major Customers" that may be disclosed elsewhere (for instance, segment disclosures).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

-Section 50

-Paragraph 16

-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6327-108592

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

-Section 50

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6404-108592

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

-Section 50

-Paragraph 18

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6351-108592

+ Details

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 21

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13537-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

-Section 50

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6404-108592

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13531-108611

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

-Section 50

-Paragraph 18

-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6351-108592

+ Details

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- Definition

The excess of replacement or current cost over the stated LIFO (last in first out) inventory value when the LIFO inventory method is utilized.

+ References

+ Details

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Balance Type:	debit
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- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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- Definition

Amount of difference between inventory at lower of LIFO cost or market and inventory at lower of other inventory accounting method cost or market, for example, but not limited to, FIFO or average cost.

+ References

+ Details

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- 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://www.xbrl.org/2003/role/presentationRef

-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=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-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=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-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=6877327&loc=d3e13212-122682

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 5

-Section L

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- Definition

The percentage of LIFO (last in first out) inventory to total inventory as of the balance sheet date if other than 100 percent.

+ References

No definition available.

+ Details

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- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

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- Definition

The aggregate refunds recognized during an accounting period due to goods returned by customers (other than under warranty provisions). Returns are a deduction from gross revenue in arriving at net revenue.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1(a))

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

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- Details

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- Details

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Significant Accounting Policies (Narrative) (Details) (USD $)	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Significant Accounting Policies [Line Items]
LIFO inventory, percentage	73.00%us-gaap_PercentageOfLIFOInventory	67.00%us-gaap_PercentageOfLIFOInventory
LIFO reserve	$ 768,000,000us-gaap_InventoryLIFOReserve	$ 431,000,000us-gaap_InventoryLIFOReserve
LIFO expense	337,000,000	311,000,000	13,000,000
LIFO inventory, excess of market			60,000,000
LIFO to market adjustment		60,000,000mck_InventoryLIFOtoMarketAdjustment
Capitalized software held for sale, useful life	3 years
Capitalized software held for internal use, net	435,000,000us-gaap_CapitalizedComputerSoftwareNet	508,000,000us-gaap_CapitalizedComputerSoftwareNet
Capitalized software held for internal use, accumulated amortization	1,112,000,000	1,004,000,000
Sales returns from customers	2,700,000,000us-gaap_SalesReturnsGoods	1,900,000,000us-gaap_SalesReturnsGoods	1,900,000,000us-gaap_SalesReturnsGoods
Supplier reserves	$ 167,000,000mck_SupplierReserves	$ 181,000,000mck_SupplierReserves
Tax benefits recognized from uncertain tax positions, threshold	50.00%
Business combinations, percent consolidated	100.00%
Minimum [Member]
Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	1 year
Intangible assets, useful life	1 year
Capitalized software held for internal use, useful life	1 year
Maximum [Member]
Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	30 years
Intangible assets, useful life	38 years
Capitalized software held for internal use, useful life	10 years
Sales Revenue, Net [Member] \| Customer Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Concentration risk, percentage	44.00%
Accounts Receivable [Member] \| Customer Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Concentration risk, percentage	36.00%
Largest Customer [Member] \| Sales Revenue, Net [Member] \| Customer Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Concentration risk, percentage	15.00%
Concentration risk, customer name	CVS Caremark Corporation (“CVS”)
Largest Customer [Member] \| Accounts Receivable [Member] \| Customer Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Concentration risk, percentage	14.00%
Concentration risk, customer name	CVS