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Document and Entity Information (USD $)
 12 Months Ended
Mar. 31, 2012
May 11, 2012
Sep. 24, 2011
Document And Entity Information [Abstract]      
Entity Registrant Name MONRO MUFFLER BRAKE INC    
Entity Central Index Key 0000876427    
Document Type 10-K    
Document Period End Date Mar. 31, 2012    
Amendment Flag false    
Document Fiscal Year Focus 2012    
Document Fiscal Period Focus FY    
Current Fiscal Year End Date --03-31    
Entity Well Known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Large Accelerated Filer    
Entity Public Float     $ 991,909,000
Entity Common Stock Shares Outstanding   30,897,356