Available increase in aggregate amount borrowed

No definition available.

Name:	msm_AvailableIncreaseInAggregateAmountBorrowed
Namespace Prefix:	msm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum Consolidated Leverage Ratio To Indebtedness

+ References

No definition available.

+ Details

Name:	msm_MaximumConsolidatedLeverageRatioToIndebtedness
Namespace Prefix:	msm_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum Consolidated Interest Coverage Ratio Of Ebitda To Interest Expense

+ References

No definition available.

+ Details

Name:	msm_MinimumConsolidatedInterestCoverageRatioOfEbitdaToInterestExpense
Namespace Prefix:	msm_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Usage fee, percent

+ References

No definition available.

+ Details

Name:	msm_UsageFeePercent
Namespace Prefix:	msm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

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

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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 210.5-02.22(a)(2))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount borrowed under the credit facility as of the balance sheet date.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

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

- Definition

The effective interest rate during the reporting 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 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum amount borrowed under the credit facility at any time during the period.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601

+ Details

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

- Definition

Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(f))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph f

-Article 4

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 14

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3255-108585

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of cash outflow for payment of an obligation from a lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(f))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph f

-Article 4

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3291-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	credit
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Debt And Capital Lease Obligations (Credit Facility) (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended		12 Months Ended					9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended
	May 31, 2014	Jun. 01, 2013	Aug. 31, 2013	Aug. 31, 2013 Revolving Credit Facility [Member]	May 31, 2014 Revolving Credit Facility [Member]	May 31, 2014 Term Loan [Member]	Aug. 31, 2013 Term Loan [Member]	May 31, 2014 New Credit Facility [Member]	Apr. 22, 2013 New Credit Facility [Member]	May 31, 2014 New Credit Facility [Member] Revolving Credit Facility [Member]	Apr. 22, 2013 New Credit Facility [Member] Revolving Credit Facility [Member]	May 31, 2014 New Credit Facility [Member] Term Loan [Member]	Apr. 22, 2013 New Credit Facility [Member] Term Loan [Member]	May 31, 2014 New Credit Facility [Member] Letter of Credit [Member]	May 31, 2014 Former Credit Facility [Member]	May 31, 2014 LIBOR [Member] One-Month Interest Period [Member]	May 31, 2014 Federal Funds Effective Rate [Member] New Credit Facility [Member]	May 31, 2014 Minimum [Member] New Credit Facility [Member]	May 31, 2014 Minimum [Member] New Credit Facility [Member] Letter of Credit [Member]	May 31, 2014 Minimum [Member] LIBOR [Member] New Credit Facility [Member]	May 31, 2014 Minimum [Member] Leverage Ratio Margin [Member]	May 31, 2014 Maximum [Member] New Credit Facility [Member]	May 31, 2014 Maximum [Member] New Credit Facility [Member] Letter of Credit [Member]	May 31, 2014 Maximum [Member] LIBOR [Member] New Credit Facility [Member]	May 31, 2014 Maximum [Member] Leverage Ratio Margin [Member]
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity									$ 650,000		$ 400,000		$ 250,000		$ 200,000
Maturity date								Apr. 22, 2018
Credit facility, expiration term										5 years		5 years
Available increase in amount borrowed								200,000
Percentage points in addition to reference rate used in computation of variable rate on debt instrument																1.00%	0.50%			1.00%	0.00%			1.375%	0.375%
Usage fee, percent																			1.00%				1.375%
Quarterly undrawn fee														0.125%				0.10%				0.20%
Borrowing rate under Credit Facility								1.15%
Maximum consolidated leverage ratio of total indebtedness to EBITDA								3.00
Minimum consolidated interest coverage ratio of EBITDA to total interest expense								3.00
Payments under revolving loans from credit facility	45,000		120,000
Borrowings under Credit Facility	50,000	370,000
Amount borrowed during the period				0
Current maturities			12,500					26,875
Outstanding balance					$ 5,000	$ 240,625	$ 250,000