Document and Entity Information (USD $)	12 Months Ended
	May 31, 2011	Jun. 30, 2011	Nov. 30, 2010
Document and Entity Information
Entity Registrant Name	AAR CORP
Entity Central Index Key	0000001750
Document Type	10-K
Document Period End Date	May 31, 2011
Amendment Flag	false
Current Fiscal Year End Date	--05-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 934,567,976
Entity Common Stock, Shares Outstanding		39,682,142
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	FY