Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Nov. 30, 2018	Nov. 30, 2017
Income Statement [Abstract]
Revenues	$ 564,020	$ 483,279
Operating expense:
Cost of goods sold	490,132	406,251
Selling, general and administrative	51,419	51,043
(Income) from joint ventures	(485)	(450)
Other asset impairment charges (recoveries), net	63	(88)
Restructuring charges and other exit-related activities	202	100
Operating income	22,689	26,423
Interest expense	(1,906)	(2,059)
Other income, net	23	849
Income from continuing operations before income taxes	20,806	25,213
Income tax expense	(4,116)	(5,957)
Income from continuing operations	16,690	19,256
Loss from discontinued operations, net of tax	(72)	(35)
Net income	16,618	19,221
Net income attributable to noncontrolling interests	(430)	(857)
Net income attributable to SSI	$ 16,188	$ 18,364
Net income per share attributable to SSI Basic:
Income per share from continuing operations attributable to SSI (in dollars per share)	$ 0.59	$ 0.66
Loss per share from discontinued operations attributable to SSI (in dollars per share)	0	0
Net income per share attributable to SSI (in dollars per share)	0.59	0.66
Net income per share attributable to SSI Diluted:
Income per share from continuing operations attributable to SSI (in dollars per share)	0.57	0.64
Loss per share from discontinued operations attributable to SSI (in dollars per share)	0	0
Net income per share attributable to SSI (in dollars per share)	$ 0.57	$ 0.64
Weighted average number of common shares:
Basic (shares)	27,505	27,695
Diluted (Shares)	28,364	28,662
Dividends declared per common share (in dollars per share)	$ 0.1875	$ 0.1875