Document and Entity Information - USD ($)
12 Months Ended
Sep. 30, 2017
Nov. 27, 2017
Apr. 01, 2017
Document And Entity Information [Abstract]      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Sep. 30, 2017    
Entity Registrant Name PTC Inc.    
Entity Central Index Key 0000857005    
Current Fiscal Year End Date --09-30    
Document Fiscal Year Focus 2017    
Document Fiscal Period Focus FY    
Entity Filer Category Large Accelerated Filer    
Entity Common Stock, Shares Outstanding   116,125,277 115,807,774
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Public Float     $ 6,020,802,164