Income Taxes - Rollforward of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Aug. 31, 2019	Aug. 31, 2018	Aug. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	$ 91,135	$ 37,830	$ 37,105
Additions attributable to current year tax positions	14,162	3,640	725
Additions attributable to prior year tax positions	0	49,665	0
Reductions attributable to prior year tax positions	(4,169)	0	0
Balance at end of period	$ 101,128	$ 91,135	$ 37,830