Annual report pursuant to Section 13 and 15(d)

Document and Entity Information

Document and Entity Information - USD ($)
12 Months Ended
Sep. 30, 2018
Nov. 14, 2018
Mar. 31, 2018
Document and Entity Information      
Entity Registrant Name MAXIMUS INC    
Entity Central Index Key 0001032220    
Document Type 10-K    
Document Period End Date Sep. 30, 2018    
Amendment Flag false    
Current Fiscal Year End Date --09-30    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Large Accelerated Filer    
Entity Emerging Growth Company false    
Entity Smaller Reporting Company false    
Entity Shell Company false    
Entity Public Float     $ 4,291,433,990
Entity Common Stock, Shares Outstanding   64,133,318  
Document Fiscal Year Focus 2018    
Document Fiscal Period Focus FY