v3.10.0.1
Document And Entity Information - shares
9 Months Ended
Jun. 30, 2018
Aug. 10, 2018
Document And Entity Information [Abstract]    
Entity Registrant Name Oncobiologics, Inc.  
Entity Central Index Key 0001649989  
Trading Symbol ons  
Current Fiscal Year End Date --09-30  
Entity Filer Category Smaller Reporting Company  
Entity Common Stock, Shares Outstanding   72,198,468
Document Type 10-Q  
Document Period End Date Jun. 30, 2018  
Amendment Flag false  
Document Fiscal Year Focus 2018  
Document Fiscal Period Focus Q3