Document and Entity Information
12 Months Ended
Sep. 30, 2018
Document And Entity Information [Abstract]  
Document Type 20-F
Amendment Flag false
Document Period End Date Sep. 30, 2018
Document Fiscal Year Focus 2018
Document Fiscal Period Focus FY
Trading Symbol DOX
Entity Registrant Name AMDOCS LTD
Entity Central Index Key 0001062579
Current Fiscal Year End Date --09-30
Entity Well-known Seasoned Issuer Yes
Entity Current Reporting Status Yes
Entity Filer Category Large Accelerated Filer
Entity Shell Company false
Entity Emerging Growth Company false
Entity Common Stock, Shares Outstanding 140,176,828