Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended	9 Months Ended
	May 31, 2020 USD ($)	May 31, 2020 USD ($) segment	May 31, 2019 USD ($)	Sep. 01, 2019 USD ($)	Aug. 31, 2019 USD ($)	Aug. 31, 2017 USD ($)
Significant Accounting Policies [Line Items]
Number of operating segments | segment		2
Number of reportable segments | segment		2
Operating lease right-of-use assets	$ 127,418,000	$ 127,418,000
Operating lease liabilities	130,646,000	130,646,000
Cash and cash equivalents	307,655,000	307,655,000			$ 12,377,000
Bank Overdrafts					27,000,000
Repayment of Advances with Scrap Metal		7,000,000	$ 12,000,000
Insurance receivable	5,000,000	5,000,000			89,000,000
Investment, Original Cost						$ 6,000,000
Asset impairment charges	2,227,000	4,321,000	$ 63,000
Cash, FDIC Insured Amount	250,000	250,000
Customer Issued Letters Of Credit	72,000,000	72,000,000			49,000,000
Prepaid Expenses and Other Current Assets
Significant Accounting Policies [Line Items]
Prepaid Expense	26,000,000	26,000,000			23,000,000
Other Assets | AMR
Significant Accounting Policies [Line Items]
Investment, Carrying Value	6,000,000	6,000,000			$ 6,000,000
Maximum
Significant Accounting Policies [Line Items]
Bank Overdrafts	$ 1,000,000	$ 1,000,000
Accounting Standards Update 2016-02
Significant Accounting Policies [Line Items]
Operating lease right-of-use assets				$ 126,000,000
Operating lease liabilities				$ 128,000,000