Document and Entity Information - USD ($)
 12 Months Ended
Jul. 31, 2018
Aug. 31, 2018
Jan. 31, 2018
Document and Entity Information      
Entity Registrant Name CANTEL MEDICAL CORP    
Entity Central Index Key 0000019446    
Document Type 10-K    
Document Period End Date Jul. 31, 2018    
Amendment Flag false    
Current Fiscal Year End Date --07-31    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Large Accelerated Filer    
Entity Public Float     $ 4,121,209,905
Entity Common Stock, Shares Outstanding   41,706,084  
Document Fiscal Year Focus 2018    
Document Fiscal Period Focus FY