Document and Entity Information Document	9 Months Ended
	May 31, 2012	Jun. 22, 2012 Common Class A [Member]	Jun. 22, 2012 Common Class B [Member]
Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	May 31, 2012
Document Fiscal Year Focus	2012
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	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		25,361,995	1,450,749