Document and Entity Information Document - shares	9 Months Ended
	May 31, 2016	Jun. 27, 2016
Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	May 31, 2016
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	Q3
Entity Registrant Name	SCHNITZER STEEL INDUSTRIES INC
Entity Central Index Key	0000912603
Current Fiscal Year End Date	--08-31
Entity Filer Category	Accelerated Filer
Class A Common Stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		26,477,926
Class B Common Stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		305,900