Document and Entity Information	9 Months Ended
	Sep. 30, 2012	Oct. 26, 2012
Document and Entity Information
Entity Registrant Name	RELIANCE STEEL & ALUMINUM CO
Entity Central Index Key	0000861884
Document Type	10-Q
Document Period End Date	Sep. 30, 2012
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		75,557,448
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q3