Condensed Consolidated Statements of Equity - USD ($) shares in Thousands, $ in Thousands	Total	Class A Common Stock	Class B Common Stock	Common Stock Class A Common Stock	Common Stock Class B Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Total SSI Shareholders’ Equity	Noncontrolling Interests
Beginning balance at Aug. 31, 2018	$ 670,110			$ 26,502	$ 200	$ 36,929	$ 639,684	$ (37,237)	$ 666,078	$ 4,032
Beginning balance (in shares) at Aug. 31, 2018				26,502	200
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	46,355						44,770		44,770	1,585
Other comprehensive loss, net of tax	(2,186)							(2,186)	(2,186)
Distributions to noncontrolling interests	(941)									(941)
Share repurchases	(10,087)			$ (413)		(9,674)			(10,087)
Share repurchase (in shares)				(413)
Issuance of restricted stock				$ 765		(765)
Issuance of restricted stock (in shares)				765
Restricted stock withheld for taxes	(7,463)			$ (278)		(7,185)			(7,463)
Restricted stock withheld for taxes (in shares)				(278)
Share-based compensation cost	13,437					13,437			13,437
Dividends	(15,521)						(15,521)		(15,521)
Ending balance at May. 31, 2019	693,704			$ 26,576	$ 200	32,742	668,933	(39,423)	689,028	4,676
Ending balance (in shares) at May. 31, 2019				26,576	200
Beginning balance at Feb. 28, 2019	680,847			$ 26,575	$ 200	29,135	658,424	(37,727)	676,607	4,240
Beginning balance (in shares) at Feb. 28, 2019				26,575	200
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	16,440						15,690		15,690	750
Other comprehensive loss, net of tax	(1,696)							(1,696)	(1,696)
Distributions to noncontrolling interests	(314)									(314)
Issuance of restricted stock				$ 2		(2)
Issuance of restricted stock (in shares)				2
Restricted stock withheld for taxes	(21)			$ (1)		(20)			(21)
Restricted stock withheld for taxes (in shares)				(1)
Share-based compensation cost	3,629					3,629			3,629
Dividends	(5,181)						(5,181)		(5,181)
Ending balance at May. 31, 2019	693,704			$ 26,576	$ 200	32,742	668,933	(39,423)	689,028	4,676
Ending balance (in shares) at May. 31, 2019				26,576	200
Beginning balance at Aug. 31, 2019	701,296			$ 26,464	$ 200	33,700	675,363	(38,763)	696,964	4,332
Beginning balance (in shares) at Aug. 31, 2019		26,464	200	26,464	200
Cumulative Effect of New Accounting Principle in Period of Adoption (Accounting Standards Update 2016-02) at Aug. 31, 2019	(463)						(463)		(463)
Adjusted beginning balance at Aug. 31, 2019	700,833			$ 26,464	$ 200	33,700	674,900	(38,763)	696,501	4,332
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(6,778)						(8,107)		(8,107)	1,329
Other comprehensive loss, net of tax	(2,136)							(2,136)	(2,136)
Distributions to noncontrolling interests	(1,940)									(1,940)
Share repurchases	(914)			$ (53)		(861)			(914)
Share repurchase (in shares)				(53)
Issuance of restricted stock				$ 762		(762)
Issuance of restricted stock (in shares)				762
Restricted stock withheld for taxes	(5,845)			$ (274)		(5,571)			(5,845)
Restricted stock withheld for taxes (in shares)				(274)
Share-based compensation cost	6,758					6,758			6,758
Dividends	(15,631)						(15,631)		(15,631)
Ending balance at May. 31, 2020	674,347			$ 26,899	$ 200	33,264	651,162	(40,899)	670,626	3,721
Ending balance (in shares) at May. 31, 2020		26,899	200	26,899	200
Beginning balance at Feb. 29, 2020	684,948			$ 26,899	$ 200	31,174	661,418	(39,040)	680,651	4,297
Beginning balance (in shares) at Feb. 29, 2020				26,899	200
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(4,717)						(4,995)		(4,995)	278
Other comprehensive loss, net of tax	(1,859)							(1,859)	(1,859)
Distributions to noncontrolling interests	(854)									(854)
Share-based compensation cost	2,090					2,090			2,090
Dividends	(5,261)						(5,261)		(5,261)
Ending balance at May. 31, 2020	$ 674,347			$ 26,899	$ 200	$ 33,264	$ 651,162	$ (40,899)	$ 670,626	$ 3,721
Ending balance (in shares) at May. 31, 2020		26,899	200	26,899	200