Document and Entity Information (USD $)	12 Months Ended
	Aug. 31, 2012	Oct. 24, 2012	Feb. 29, 2012
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Aug. 31, 2012
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	FY
Trading Symbol	GBX
Entity Registrant Name	GREENBRIER COMPANIES INC
Entity Central Index Key	0000923120
Current Fiscal Year End Date	--08-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		27,142,911
Entity Public Float			$ 609,194,356