Restructuring Costs (Narrative) (Details)	6 Months Ended
Feb. 27, 2021 store
Restructuring Costs [Abstract]
Number of locations closed	73

Restructuring and Related Cost, Number of locations closed

No definition available.

Name:	msm_RestructuringAndRelatedCostNumberOfLocationsClosed
Namespace Prefix:	msm_
Data Type:	xbrli:positiveIntegerItemType
Balance Type:	na
Period Type:	duration