Segment Information - Reconciliation of Operating Income from Segments to Consolidated (Parenthetical) (Details) - USD ($) $ in Thousands	12 Months Ended
	Aug. 31, 2020	Aug. 31, 2019	Aug. 31, 2018
Segment Reporting Information [Line Items]
Income (loss) from joint ventures	$ 834	$ 1,452	$ 1,953
AMR | Maximum
Segment Reporting Information [Line Items]
Income (loss) from joint ventures	1,000	1,000	(1,000)
CSS
Segment Reporting Information [Line Items]
Income (loss) from joint ventures	$ 1,000	$ 1,000	$ 2,000