Document and Entity Information (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Nov. 24, 2014	Mar. 31, 2014
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Sep. 30, 2014
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Trading Symbol	ARWR
Entity Registrant Name	ARROWHEAD RESEARCH CORP
Entity Central Index Key	0000879407
Current Fiscal Year End Date	--09-30
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		54,682,636
Entity Public Float			$ 760