Document And Entity Information - shares	6 Months Ended
	Mar. 02, 2019	Mar. 18, 2019
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 02, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Entity Registrant Name	MSC INDUSTRIAL DIRECT CO INC
Entity Central Index Key	0001003078
Current Fiscal Year End Date	--08-31
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Trading Symbol	msm
Class A Common Stock [Member]
Entity Common Stock, Shares Outstanding		44,976,592
Class B Common Stock [Member]
Entity Common Stock, Shares Outstanding		10,193,348