Summary Of Significant Accounting Policies (Components Of Other Intangible Assets) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Aug. 27, 2011	Aug. 28, 2010
Gross Carrying Amount, Total	$ 87,192	$ 79,946
Accumulated Amortization	(38,884)	(31,195)
Minimum [Member] \| Customer Relationships [Member]
Weighted Average Useful Life	5
Maximum [Member] \| Customer Relationships [Member]
Weighted Average Useful Life	10
Customer Relationships [Member]
Gross Carrying Amount, Finite Lived	56,460	50,300
Accumulated Amortization	(26,711)	(21,377)
Non-Compete Agreements [Member]
Weighted Average Useful Life	2
Gross Carrying Amount, Finite Lived	360
Accumulated Amortization	(23)
Contract Rights [Member]
Weighted Average Useful Life	10
Gross Carrying Amount, Finite Lived	23,100	23,100
Accumulated Amortization	(12,127)	(9,818)
Trademark [Member]
Weighted Average Useful Life	2
Gross Carrying Amount, Finite Lived	360
Accumulated Amortization	(23)
Trademarks And License Agreement [Member]
Gross Carrying Amount, Indefinite Lived	$ 6,912	$ 6,546

Intangible Assets Gross

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Namespace Prefix:	msm
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The accumulated amount of amortization of a major finite-lived intangible asset class. A major class is composed of intangible assets that can be grouped together because they are similar, either by their nature or by their use in the operations of a company.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

-Subparagraph a(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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)(1)

-URI http://asc.fasb.org/extlink&oid=6905858&loc=d3e16323-109275

+ Details

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

- Definition

Sum of the gross carrying amounts before accumulated amortization as of the balance sheet date of all intangible assets having statutory or estimated useful lives. The aggregate gross carrying amount (including any previously recognized impairment charges) of a major finite-lived intangible asset class. A major class is composed of intangible assets that can be grouped together because they are similar, either by their nature or by their use in the operations of a company.

+ References

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsGross
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The calculated weighted-average useful life of all finite-lived intangible assets.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (a)(3)

-URI http://asc.fasb.org/extlink&oid=6905858&loc=d3e16265-109275

+ Details

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Namespace Prefix:	us-gaap
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Definition

Sum of the carrying amounts (original costs for current and prior period additions adjusted for impairment, if any) as of the balance sheet date of intangible assets, excluding goodwill, having a projected indefinite period of benefit.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6905858&loc=d3e16323-109275

+ Details

Name:	us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant