Document and Entity Information	3 Months Ended
	Aug. 31, 2017 shares
Document and Entity Information
Entity Registrant Name	AAR CORP
Entity Central Index Key	0000001750
Document Type	10-Q
Document Period End Date	Aug. 31, 2017
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	34,622,093
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q1