Basis Of Presentation (Policy)	3 Months Ended
Nov. 30, 2019
Basis Of Presentation [Abstract]
Principles Of Consolidation	Principles of Consolidation The condensed consolidated financial statements include the accounts of MSC Industrial Direct Co., Inc., its wholly owned subsidiaries and entities in which it maintains a controlling financial interest. All significant intercompany balances and transactions have been eliminated in consolidation.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements Effective September 2, 2018, the Company adopted the Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (Topic 606) as subsequently amended. This ASU outlines a single comprehensive model for entities to use in the accounting for revenue arising from contracts with customers and supersede prior revenue recognition guidance, including industry-specific guidance. Revenue continues to be recognized when products are shipped to the customer and the customer obtains control of the products, and the adoption of this ASU, using the modified retrospective approach, had no impact on the Company’s opening retained earnings. The Company reports its sales net of estimated sales returns and sales incentives. Sales tax collected from customers is excluded from net sales. Additional information and disclosures required by this new standard are contained in Note 2, “Revenue.” Effective September 2, 2018, the Company adopted ASU 2017-01, Business Combinations (Topic 805), which clarifies the definition of a business to assist entities with evaluating when a set of transferred assets and activities is considered a business. This standard was applied to business combinations that occurred beginning September 2, 2018. Effective September 1, 2019, the Company adopted 2016-02, Leases (Topic 842) as subsequently amended. This is a comprehensive new standard that amends various aspects of existing accounting guidance for leases, including the recognition of a right-of-use asset and a lease liability on the balance sheet and disclosing key information about leasing arrangements. The Company utilized the optional transition method set forth in ASU 2018-11 that allows entities to initially apply the new lease accounting standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Therefore, the adoption did not require restatement of prior periods. In addition, the Company elected the transition package of practical expedients permitted within the standard, which allowed it to carry forward the historical lease classification for arrangements that commenced prior to the effective date. As a result of the adoption of ASC 842 on September 1, 2019, the Company recorded both operating lease assets of $61,212 and operating lease liabilities of $60,730. The adoption of ASC 842 had an immaterial impact on the Company’s Condensed Consolidated Statement of Income and Condensed Consolidated Statement of Cash Flows for the thirteen-week period ended November 30, 2019. The adoption of this standard also resulted in a change in the naming convention for leases classified historically as capital leases. These leases are now referred to as finance leases. See Note 7 “Leases” for additional qualitative and quantitative information about the Company's leases.
Accounting Pronouncements Not Yet Adopted	Accounting Pronouncements Not Yet Adopted In June 2016, the FASB issued its final standard on measurement of credit losses on financial instruments. This standard, issued as ASU 2016-13, Financial Instruments – Credit Losses (Topic 326), requires that an entity measure impairment of certain financial instruments, including trade receivables, based on expected losses rather than incurred losses. This update is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, with early adoption permitted for financial statement periods beginning after December 15, 2019. The new standard is effective for the Company for its fiscal year 2021. The Company is currently evaluating the standard to determine the impact, if any, of adoption to is consolidated financial statements. Other pronouncements issued by the FASB or other authoritative accounting standards groups with future effective dates are either not applicable or are not expected to be significant to the Company’s financial position, results of operations or cash flows.
Reclassification	Reclassification Certain of the prior period line items contained in the Condensed Consolidated Statements of Shareholders’ Equity were condensed to conform to the Company’s current period presentation. The Company combined the “Exercise of common stock options”, the “Common stock issued under associate stock purchase plan”, the “Shares issued upon vesting of restricted stock units, including dividend equivalent units”, and the “Stock-based compensation”, line items into a single line titled “Associate Incentive Plans”. These reclassifications did not affect the total amount of Shareholders’ Equity.

Basis Of Presentation (Policy)

3 Months Ended

Nov. 30, 2019

Principles of Consolidation

The condensed consolidated financial statements include the accounts of MSC Industrial Direct Co., Inc., its wholly owned subsidiaries and entities in which it maintains a controlling financial interest. All significant intercompany balances and transactions have been eliminated in consolidation.

Recently Adopted Accounting Pronouncements

Effective September 2, 2018, the Company adopted the Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (Topic 606) as subsequently amended. This ASU outlines a single comprehensive model for entities to use in the accounting for revenue arising from contracts with customers and supersede prior revenue recognition guidance, including industry-specific guidance. Revenue continues to be recognized when products are shipped to the customer and the customer obtains control of the products, and the adoption of this ASU, using the modified retrospective approach, had no impact on the Company’s opening retained earnings. The Company reports its sales net of estimated sales returns and sales incentives. Sales tax collected from customers is excluded from net sales. Additional information and disclosures required by this new standard are contained in Note 2, “Revenue.”

Effective September 2, 2018, the Company adopted ASU 2017-01, Business Combinations (Topic 805), which clarifies the definition of a business to assist entities with evaluating when a set of transferred assets and activities is considered a business. This standard was applied to business combinations that occurred beginning September 2, 2018.

Effective September 1, 2019, the Company adopted 2016-02, Leases (Topic 842) as subsequently amended. This is a comprehensive new standard that amends various aspects of existing accounting guidance for leases, including the recognition of a right-of-use asset and a lease liability on the balance sheet and disclosing key information about leasing arrangements. The Company utilized the optional transition method set forth in ASU 2018-11 that allows entities to initially apply the new lease accounting standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Therefore, the adoption did not require restatement of prior periods. In addition, the Company elected the transition package of practical expedients permitted within the standard, which allowed it to carry forward the historical lease classification for arrangements that commenced prior to the effective date.

As a result of the adoption of ASC 842 on September 1, 2019, the Company recorded both operating lease assets of $61,212 and operating lease liabilities of $60,730. The adoption of ASC 842 had an immaterial impact on the Company’s Condensed Consolidated Statement of Income and Condensed Consolidated Statement of Cash Flows for the thirteen-week period ended November 30, 2019. The adoption of this standard also resulted in a change in the naming convention for leases classified historically as capital leases. These leases are now referred to as finance leases. See Note 7 “Leases” for additional qualitative and quantitative information about the Company's leases.

Accounting Pronouncements Not Yet Adopted

In June 2016, the FASB issued its final standard on measurement of credit losses on financial instruments. This standard, issued as ASU 2016-13, Financial Instruments – Credit Losses (Topic 326), requires that an entity measure impairment of certain financial instruments, including trade receivables, based on expected losses rather than incurred losses. This update is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, with early adoption permitted for financial statement periods beginning after December 15, 2019. The new standard is effective for the Company for its fiscal year 2021. The Company is currently evaluating the standard to determine the impact, if any, of adoption to is consolidated financial statements.

Other pronouncements issued by the FASB or other authoritative accounting standards groups with future effective dates are either not applicable or are not expected to be significant to the Company’s financial position, results of operations or cash flows.

Reclassification

Certain of the prior period line items contained in the Condensed Consolidated Statements of Shareholders’ Equity were condensed to conform to the Company’s current period presentation. The Company combined the “Exercise of common stock options”, the “Common stock issued under associate stock purchase plan”, the “Shares issued upon vesting of restricted stock units, including dividend equivalent units”, and the “Stock-based compensation”, line items into a single line titled “Associate Incentive Plans”. These reclassifications did not affect the total amount of Shareholders’ Equity.