Description of the Plan - Narrative (Details) - EBP 003	12 Months Ended
Dec. 31, 2025 USD ($) yr investment h	Dec. 31, 2024 USD ($)
EBP, Description of Plan [Line Items]
EBP, employer contribution, minimum age	18 years
EBP, employer contribution, matching percentage	50.00%
EBP, employer contribution, participant compensation matched, percentage	6.00%
EBP, requisite service period \| h	1,000
EBP, employer contribution maximum vesting age \| yr	65
EBP, employer contribution vesting percentage	100.00%
EBP, forfeited nonvested account	$ 32,730	$ 30,418
EBP, forfeited nonvested account, decrease from employer contribution	228,000	$ 206,917
EBP, note receivable from participant, account, minimum borrowing, amount	$ 1,000
EBP, note receivable from participant, account, maximum borrowing, to total account, percentage	50.00%
EBP, note receivable from participant, account, maximum borrowing, amount	$ 50,000
EBP, note receivable from participant, account, basis spread on variable rate	1.00%
EBP, asset held for investment, participant loan, interest rate	7.75%
EBP, maximum repayment period	10 years
EBP, still employed, participant age for distribution \| yr	59.5
EBP, voluntary cash-out limit	$ 7,000
EBP, involuntary cash-out limit	$ 1,000
Mutual funds
EBP, Description of Plan [Line Items]
EBP, number of investment options offered \| investment	25
Common collective trusts
EBP, Description of Plan [Line Items]
EBP, number of investment options offered \| investment	2
Minimum
EBP, Description of Plan [Line Items]
EBP, participant contribution, pretax, maximum annual compensation to total compensation, percentage	1.00%
EBP, asset held for investment, participant loan, interest rate	4.25%	4.25%
Maximum
EBP, Description of Plan [Line Items]
EBP, participant contribution, pretax, maximum annual compensation to total compensation, percentage	40.00%
EBP, asset held for investment, participant loan, interest rate	9.50%	9.50%

EBP, Employer Contribution Maximum Vesting Age

No definition available.

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- Definition

EBP, Employer Contribution, Minimum Age

+ References

No definition available.

+ Details

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- Definition

EBP, Employer Contribution Vesting Percentage

+ References

No definition available.

+ Details

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- Definition

EBP, Involuntary Cash-out Limit

+ References

No definition available.

+ Details

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- Definition

EBP, Involuntary Cash-out Limit, Maximum Amount

+ References

No definition available.

+ Details

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- Definition

EBP, Maximum Repayment Period

+ References

No definition available.

+ Details

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- Definition

EBP, Note Receivable From Participant, Account, Basis Spread On Variable Rate

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

EBP, Number Of Investment Options Offered

+ References

No definition available.

+ Details

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Namespace Prefix:	msm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

EBP, Participant Distribution Minimum Age

+ References

No definition available.

+ Details

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- Definition

EBP, Requisite Service Period, Number Of Hours

+ References

No definition available.

+ Details

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- 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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478416/962-205-50-1

+ Details

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

- Definition

Percentage of employer matching contribution on eligible participant contribution to employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

+ Details

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Period Type:	duration

- Definition

Percentage of participant compensation eligible for employer matching contribution for participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

+ Details

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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of plan asset, in forfeited nonvested account, no longer allocated to participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

+ Details

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

- Definition

Amount of decrease in forfeited nonvested account of employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) from employer contribution.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 962
-SubTopic 325
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478873/962-325-55-17

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (j)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478416/962-205-50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6A-04(5)(c))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477804/962-205-S99-1

+ Details

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Period Type:	duration

- Definition

Amount of maximum account balance that participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) can borrow.

+ References

+ Details

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- Definition

Percentage of maximum account balance that participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) can borrow to total participant account balance.

+ References

+ Details

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- Definition

Amount of minimum account balance that participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) can borrow.

+ References

+ Details

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Period Type:	instant

- Definition

Percentage of maximum pretax annual compensation that participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)), is permitted to contribute to total pretax annual compensation.

+ References

+ Details

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Namespace Prefix:	us-gaap-ebp_
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Period Type:	duration

- Definition

Interest rate on participant loan in schedule of asset held for investment of employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Employee Retirement Income Security Act of 1974
-Number 2520
-Section 103
-Subsection 10
-Paragraph b
-Subparagraph (1)(i)(D)
-Publisher DOL-EBSA

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6A-05(a)(Schedule I))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477804/962-205-S99-1

+ Details

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- Details

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- Details

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