Document and Entity Information
3 Months Ended
Dec. 31, 2013
Jan. 31, 2014
Document Document And Entity Information [Line Items]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Dec. 31, 2013  
Document Fiscal Year Focus 2014  
Document Fiscal Period Focus Q1  
Trading Symbol ARWR  
Entity Registrant Name ARROWHEAD RESEARCH CORP  
Entity Central Index Key 0000879407  
Current Fiscal Year End Date --09-30  
Entity Filer Category Smaller Reporting Company  
Entity Common Stock, Shares Outstanding   39,687,033