Document and Entity Information - USD ($)	12 Months Ended
	Aug. 31, 2016	Oct. 21, 2016	Feb. 29, 2016
Entity Information [Line Items]
Entity Registrant Name	SCHNITZER STEEL INDUSTRIES INC
Entity Central Index Key	0000912603
Current Fiscal Year End Date	--08-31
Entity Filer Category	Accelerated Filer
Document Type	10-K
Document Period End Date	Aug. 31, 2016
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 379,176,246
Class A Common Stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		26,593,816
Class B Common Stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		200,000