Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Feb. 28, 2018	Feb. 28, 2017	Feb. 28, 2018	Feb. 28, 2017
Income Statement [Abstract]
Revenues		$ 559,443	$ 382,084	$ 1,042,722	$ 716,245
Operating expense:
Cost of goods sold		472,462	326,804	878,713	622,696
Selling, general and administrative		53,638	43,823	104,681	81,315
(Income) from joint ventures		(106)	(2,220)	(556)	(2,632)
Other asset impairment charges (recoveries), net		0	0	(88)	401
Restructuring charges and other exit-related activities		91	(494)	191	(293)
Operating income		33,358	14,171	59,781	14,758
Interest expense		(2,281)	(2,097)	(4,340)	(3,838)
Other income, net		101	357	950	794
Income from continuing operations before income taxes		31,178	12,431	56,391	11,714
Income tax (expense) benefit		10,577	(637)	4,620	(575)
Income from continuing operations		41,755	11,794	61,011	11,139
Income (loss) from discontinued operations, net of tax		164	(95)	129	(148)
Net income		41,919	11,699	61,140	10,991
Net income attributable to noncontrolling interests		(903)	(662)	(1,760)	(1,280)
Net income attributable to SSI		$ 41,016	$ 11,037	$ 59,380	$ 9,711
Net income (loss) per share attributable to SSI Basic:
Income per share from continuing operations attributable to SSI		$ 1.47	$ 0.40	$ 2.14	$ 0.36
Income (loss) per share from discontinued operations attributable to SSI		0.01	0.00	0.00	(0.01)
Net income per share attributable to SSI		1.48	0.40	2.14	0.35
Net income (loss) per share attributable to SSI Diluted:
Income per share from continuing operations attributable to SSI		1.42	0.40	2.06	0.35
Income (loss) per share from discontinued operations attributable to SSI		0.01	0.00	0.00	(0.01)
Net income per share attributable to SSI	[1]	$ 1.42	$ 0.40	$ 2.07	$ 0.35
Weighted average number of common shares:
Basic		27,797	27,524	27,745	27,447
Diluted		28,805	27,864	28,737	27,814
Dividends declared per common share		$ 0.1875	$ 0.1875	$ 0.375	$ 0.375

[1] May not foot due to rounding.