Net Income (Loss) Per Share - Schedule of Basic and Diluted Net Income (Loss) Per Share (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Nov. 30, 2020	Nov. 30, 2019
Earnings Per Share [Abstract]
Income (loss) from continuing operations	$ 15,106	$ (6,593)
Net income attributable to noncontrolling interests	(960)	(430)
Income (loss) from continuing operations attributable to SSI shareholders	14,146	(7,023)
(Loss) income from discontinued operations, net of tax	(42)	28
Net income (loss) attributable to SSI shareholders	$ 14,104	$ (6,995)
Computation of shares:
Weighted average common shares outstanding, basic	27,807	27,515
Incremental common shares attributable to dilutive performance share awards, restricted stock units and deferred stock units	678
Weighted average common shares outstanding, diluted	28,485	27,515