Document and Entity Information	9 Months Ended
	Feb. 28, 2018 shares
Document and Entity Information
Entity Registrant Name	AAR CORP
Entity Central Index Key	0000001750
Document Type	10-Q
Document Period End Date	Feb. 28, 2018
Amendment Flag	false
Current Fiscal Year End Date	--05-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	34,638,738
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3