Revenue - Effect of New Revenue Guidance, Impact on Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended
	Nov. 30, 2018	Nov. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net revenue	$ 6,506,275	$ 5,585,532
Cost of revenue	5,986,625	5,116,247
Operating income	216,710	145,754
Income tax expense	40,813	43,520
Net income	124,074	$ 63,919
Balance without the adoption of ASU 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net revenue	6,243,735
Cost of revenue	5,760,456
Operating income	180,339
Income tax expense	39,916
Net income	$ 88,600