Document and Entity Information - USD ($)	12 Months Ended
	May. 31, 2015	Jul. 24, 2015	Nov. 28, 2014
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	May 31, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	FY
Trading Symbol	WOR
Entity Registrant Name	WORTHINGTON INDUSTRIES INC
Entity Central Index Key	0000108516
Current Fiscal Year End Date	--05-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		65,408,865
Entity Public Float			$ 1,784,231,417