Cover - shares	3 Months Ended
	Dec. 31, 2024	Feb. 03, 2025
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Dec. 31, 2024
Document Transition Report	false
Entity File Number	001-38042
Entity Registrant Name	ARROWHEAD PHARMACEUTICALS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-0408024
Entity Address, Address Line One	177 E. Colorado Blvd
Entity Address, Address Line Two	Suite 700
Entity Address, City or Town	Pasadena
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	91105
City Area Code	626
Local Phone Number	304-3400
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	ARWR
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		126,098,111
Entity Central Index Key	0000879407
Current Fiscal Year End Date	--09-30
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	Q1
Amendment Flag	false