Subsequent Events	6 Months Ended
Mar. 31, 2022
Subsequent Events [Abstract]
Subsequent Events	NOTE 11. SUBSEQUENT EVENTS Visirna Therapeutics, Inc. On April 25, 2022, Arrowhead Pharmaceuticals, Inc., entered into definitive agreements to form a joint venture, Visirna Therapeutics, Inc. (“Visirna”) with Vivo Capital (“Vivo”) through which the Company and Vivo intend to expand the reach of innovative medicines in Greater China. The Company licensed to Visirna the exclusive rights to develop and commercialize four of Arrowhead’s investigational RNA interference (RNAi) therapeutic candidates for cardiometabolic diseases in mainland China, Hong Kong, Macau, and Taiwan. Vivo will provide initial funding of $60.0 million to Visirna. The Company has a majority stake in Visirna following this initial funding and is further eligible to receive potential royalties on commercial sales.

The entire disclosure for significant events or transactions that occurred after the balance sheet date through the date the financial statements were issued or the date the financial statements were available to be issued. Examples include: the sale of a capital stock issue, purchase of a business, settlement of litigation, catastrophic loss, significant foreign exchange rate changes, loans to insiders or affiliates, and transactions not in the ordinary course of business.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 855
-URI http://asc.fasb.org/topic&trid=2122774

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 855
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6842918&loc=SL6314017-165662

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