Description of Business and Summary of Significant Accounting Policies (Fulfillment Costs) (Details) - USD ($)	12 Months Ended
	Aug. 31, 2020	Aug. 31, 2019
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Capitalized costs	$ 85,300,000	$ 67,100,000
Amortization of fulfillment cost	56,600,000	48,600,000
Impairment costs	$ 0	$ 0
Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation, period	1 year
Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation, period	3 years