Significant Accounting policies - Additional Information (Detail) $ in Thousands	12 Months Ended
	Aug. 31, 2019 USD ($) Store Product shares	Aug. 25, 2018 USD ($) shares	Aug. 26, 2017 USD ($) shares	Aug. 27, 2016 USD ($)
Significant Accounting Policies [Line Items]
Number of stores with commercial sales program | Store	4,893
Description of reporting periods	Fiscal Year: The Company’s fiscal year consists of 52 or 53 weeks ending on the last Saturday in August. Fiscal 2019 represented 53 weeks. Fiscal 2018 and 2017 represented 52 weeks.
Cash and cash equivalents	$ 176,300	$ 217,824	$ 293,270	$ 189,734
Allowances for uncollectible accounts	8,500	6,100
Unrecorded adjustment for LIFO value in excess of replacement value	404,900	452,400
Self insurance reserve	207,000	203,100
Deferred rent	$ 159,900	139,600
Measure of income tax benefit for uncertain income tax positions	more than 50%
Advertising expense, net of vendor promotional funds	$ 87,500	95,200	93,100
Vendor promotional funds, which reduced advertising expense	$ 32,200	25,300	$ 28,300
Limited warranty period, minimum period (Days)	30 days
Products accounted for total revenues	one class of similar products accounted for approximately 13 percent of the Company's total revenues, No other class of similar products accounted for 10 percent or more of total revenues
Products accounted for total purchases	one vendor supplied approximately 12 percent of the Company's total purchases. No other class of similar products accounted for 10 percent or more of total revenues
Accounting Standards Update 2016-02 [Member]
Significant Accounting Policies [Line Items]
weighted average discount rate	3.60%
Cash Equivalents [Member]
Significant Accounting Policies [Line Items]
Maturity period of investments	90 days or less
Settlement term of credit and debit card transaction	less than five days
Credit and debit card receivables included within cash and cash equivalents	$ 59,400	$ 51,000
Product Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Number of class of similar products accounted for approximately 13% of the company's total revenues | Product	1
Stock Options [Member]
Significant Accounting Policies [Line Items]
Anti-dilutive shares excluded from the computation of earnings per share | shares	90,314	847,279	620,025
Minimum [Member]
Significant Accounting Policies [Line Items]
Amortization of intangible assets	3 years
Minimum [Member] | Accounting Standards Update 2016-02 [Member]
Significant Accounting Policies [Line Items]
ROU assets	$ 2,500
Lease Liabilities	$ 2,500
Minimum [Member] | Building [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives	40 years
Minimum [Member] | Building Improvements [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives	5 years
Minimum [Member] | Equipment [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Minimum [Member] | Product Concentration Risk [Member] | Sales Revenue, Net [Member]
Significant Accounting Policies [Line Items]
Concentration risk percentage	10.00%
Minimum [Member] | Supplier Concentration Risk [Member] | Cost of Goods, Total [Member]
Significant Accounting Policies [Line Items]
Concentration risk percentage	10.00%
Maximum [Member]
Significant Accounting Policies [Line Items]
Amortization of intangible assets	10 years
Maximum [Member] | Accounting Standards Update 2016-02 [Member]
Significant Accounting Policies [Line Items]
ROU assets	$ 2,800
Lease Liabilities	$ 2,800
Maximum [Member] | Building [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives	50 years
Maximum [Member] | Building Improvements [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives	15 years
Maximum [Member] | Equipment [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives	10 years
Maximum [Member] | Product Concentration Risk [Member] | Sales Revenue, Net [Member]
Significant Accounting Policies [Line Items]
Concentration risk percentage	13.00%
Maximum [Member] | Supplier Concentration Risk [Member] | Cost of Goods, Total [Member]
Significant Accounting Policies [Line Items]
Concentration risk percentage	12.00%
Stores in the United States Including Puerto Rico [Member]
Significant Accounting Policies [Line Items]
Number of stores | Store	5,772
Brazil [Member]
Significant Accounting Policies [Line Items]
Number of stores | Store	35
Mexico [Member]
Significant Accounting Policies [Line Items]
Number of stores | Store	604
Non-US [Member]
Significant Accounting Policies [Line Items]
Cash and cash equivalents	$ 49,900	$ 98,800