Organization and Basis of Presentation (Policies)	9 Months Ended
Jun. 30, 2012
Organization and Basis of Presentation [Abstract]
Nature of Business and Going Concern	Nature of Business and Going Concern Arrowhead Research Corporation is a nanomedicine company developing innovative therapies at the interface of biology and nanoengineering to cure disease and improve human health. Arrowhead has one of the most advanced and broadest technology platforms for therapeutics based on RNA interference (RNAi), including access to several different RNAi delivery systems and small interfering RNA (siRNA) structures in commercial development for RNAi therapeutics. This broad technology platform enables optimization of siRNA therapeutic candidates for delivery based on siRNA chemistry, tissue type, disease state, target gene and siRNA type and chemistry on a target-by-target basis. Through its acquisition of Alvos Therapeutics, Arrowhead has access to a large platform of proprietary human-derived homing peptides and the method for their discovery. These targeting peptide sequences can be linked to our siRNA delivery vehicles as well as to traditional small molecule drugs to preferentially shuttle them into target cells. Arrowhead is leveraging its in-house R&D expertise and capabilities, as well as a broad intellectual property portfolio for RNAi therapeutics, and RNAi and peptide delivery vehicles and targeting methods to seek development partnerships with other pharmaceutical and biotech companies committed to bringing RNAi therapeutics to market, as well as continuing the preclinical and clinical development of its own clinical candidates. Arrowhead’s non-RNAi development programs include a unique therapeutic candidate that shows promise in pre-clinical studies for the potential treatment of obesity and advanced bioactive materials for the regeneration of injured tissues. Arrowhead operates a wholly-owned subsidiary, Arrowhead Madison Inc., which operates a lab facility in Madison, Wisconsin, supporting the company’s initiatives including the development of RNAi therapeutics. In addition to its wholly owned subsidiaries, Arrowhead Madison and Alvos Therapeutics, Arrowhead operates two majority-owned subsidiaries, Calando, a leader in delivering small interfering RNAs for gene silencing, and Ablaris, an anti-obesity therapeutics company, and has minority investments in Nanotope, a regenerative medicine company and Leonardo, a multistage drug delivery company.
Liquidity	Liquidity Arrowhead has historically financed its operations through the sale of securities of Arrowhead and its Subsidiaries. Development activities have required significant capital investment since the Company’s inception and we expect our current portfolio companies to continue to require cash investment in fiscal 2012 and beyond to continue development. At June 30, 2012, the Company had $2.3 million in cash to fund operations. During the nine months ended June 30, 2012, the Company’s cash position decreased by $5.2 million. The Company received cash from the issuance of equity of $5.4 million, cash from the sale of its holdings of stock in Wisepower Co. Ltd of $0.5 million, and cash collections from revenue of $0.2 million. The company had cash outflow of $10.6 million related to its continuing operating activities and capital expenditures of $0.4 million. On August 13, 2012, the Company had received firm commitments for 2.3 million units at a price of $2.76 per unit in a registered offering to institutional and individual investors. Each unit consisted on one share of Arrowhead Common Stock and a warrant to purchase 0.75 share of Common Stock exercisable at $3.25 per share. Gross proceeds from the offering are expected to be approximately $6.2 million, with net proceeds of approximately $5.8 million after deducting commissions and fees. As a result of the sale of the Company’s subsidiary, Unidym, in January 2011, the Company received $2.5 million in stock of the acquirer, Wisepower Co. Ltd. (“Wisepower”) and a $2.5 million convertible bond from Wisepower, of which approximately $200,000 is owed to a third party who was a minority investor in Unidym. During the quarter ended December 31, 2011, the Company sold its remaining stock in Wisepower. The convertible bond has a face value of $2.5 million, and is convertible into Wisepower common stock at a price of $2.00 per share. The bond can be redeemed for cash on January 17, 2013, and at which time could represent an additional source of liquidity for the company. The Company had Subscriptions Receivable of $1.0 million at June 30, 2012, which are expected to be collected over the next several months. In September 2011, the Company entered into an equity line facility whereby it has the ability to draw capital up to $15 million. Through June 30, 2012, the Company has drawn approximately $1 million from this facility and has issued 181,042 shares of common stock; the Company expects to draw upon the facility from time to time, depending on cash needs and market conditions. On October 21, 2011, Arrowhead completed the acquisition of certain RNAi assets from Hoffmann-La Roche Inc. and F. Hoffmann-La Roche Ltd., including intellectual property and a research and development facility in Madison, Wisconsin. At the time of the acquisition, the Madison facility had 41 employees. Due to the costs associated with maintaining and operating the facility, including personnel costs, rent, research and development expenses, and other costs, cash expenses have increased, and it is expected that the Company will incur higher cash expenses will continue during the remainder of fiscal 2012 and beyond, relative to periods prior to the acquisition, as the Company accelerates its preclinical and clinical development efforts. Based upon the Company’s cash on hand, other sources of liquidity, as described above, and based upon the Company’s operating plan, the Company’s management anticipates that the Company will be able to satisfy the cash requirements of its operations through at least the next twelve months. The Company anticipates that further equity financings, and/or asset sales and license agreements will be necessary to continue to fund operations in the future.
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The accompanying unaudited consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial information and in accordance with the instructions to Form 10-Q and Article 8 of Regulation S-X. Accordingly, the financial statements do not include all of the information and notes required by GAAP for complete financial statements. In the opinion of management, all adjustments, including normal recurring accruals, considered necessary for a fair presentation have been included. Interim results are not necessarily indicative of results for a full year. The September 30, 2011 balance sheet was derived from audited financial statements, but does not include all disclosures required by GAAP. This financial information should be read in conjunction with the consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K for the year ended September 30, 2011. The consolidated financial statements of the Company include the accounts of Arrowhead and its wholly-owned and majority-owned Subsidiaries. Prior to April 2008, Arrowhead’s Subsidiaries included Insert Therapeutics, Inc. (“Insert”), which was merged with Calando in April 2008. The merged entity is majority-owned by Arrowhead and continues to operate under the name of Calando. Arrowhead sold its interests in Unidym and Tego in 2011 and 2009, respectively. Unidym and Tego results are included in the Income (Loss) from Discontinued Operations. Income (Loss) from Discontinued Operations also includes Aonex Technologies, Inc. (“Aonex”), sold in 2008 and Nanotechnica, Inc. (“Nanotechnica”), dissolved in 2005. All significant intercompany accounts and transactions are eliminated in consolidation, and noncontrolling interests are accounted for in the Company’s financial statements. Certain reclassifications have been made to prior period financial statements to conform to the current period presentation.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the amounts reported in the accompanying financial statements. Actual results could differ from those estimates.
Testing Goodwill for Impairment	In September 2011, the FASB issued ASU 2011-08, Testing Goodwill for Impairment (“ASU 2011-08”), which amends the guidance in ASC 350-20, Intangibles—Goodwill and Other – Goodwill. ASU 2011-08 provides entities with the option of performing a qualitative assessment before calculating the fair value of the reporting unit when testing goodwill for impairment. If the fair value of the reporting unit is determined, based on qualitative factors, to be more likely than not less than the carrying amount of the reporting unit, the entities are required to perform a two-step goodwill impairment test. ASU 2011-08 was effective for us beginning January 1, 2012. The adoption of ASU 2011-08 did not have a material effect on our consolidated financial statements or disclosures.
Fair Value Measurement	In May 2011, the Financial Accounting Standards Board (“FASB”) issued ASU 2011-04, Fair Value Measurement (“ASU 2011-04”), which amended ASC 820, Fair Value Measurements (“ASC 820”), providing a consistent definition and measurement of fair value, as well as similar disclosure requirements between U.S. GAAP and International Financial Reporting Standards. ASU 2011-04 changes certain fair value measurement principles, clarifies the application of existing fair value measurement and expands the disclosure requirements. ASU 2011-04 was effective for us beginning January 1, 2012. The adoption of ASU 2011-04 did not have a material effect on our consolidated financial statements or disclosures. In January 2010, the FASB issued Accounting Standards Update ASU No. 2010-06, Fair Value Measurements and Disclosures (Topic 820) – Improving Disclosures about Fair Value Measurements. This guidance requires new disclosures related to recurring and nonrecurring fair value measurements. The guidance requires disclosure of transfers of assets and liabilities between Level 1 and Level 2 of the fair value measurement hierarchy, including the reasons and the timing of the transfers and information on purchases, sales, issuance, and settlements on a gross basis in the reconciliation of the assets and liabilities measured under Level 3 of the fair value measurement hierarchy. The adoption of this guidance is effective for interim and annual reporting periods beginning after December 15, 2009. We have adopted this guidance in the financial statements presented herein, which did not have a material impact on our consolidated financial position or results of operations.
Revenue Recognition	In June 2010, the FASB issued ASU No. 2010-17, Revenue Recognition—Milestone Method (Topic 605): Milestone Method of Revenue Recognition. This ASU codifies the consensus reached in EITF Issue No. 08-9, “Milestone Method of Revenue Recognition.” The amendments to the Codification provide guidance on defining a milestone and determining when it may be appropriate to apply the milestone method of revenue recognition for research or development transactions. Consideration that is contingent on achievement of a milestone in its entirety may be recognized as revenue in the period in which the milestone is achieved only if the milestone is judged to meet certain criteria to be considered substantive. Milestones should be considered substantive in their entirety and may not be bifurcated. An arrangement may contain both substantive and nonsubstantive milestones, and each milestone should be evaluated individually to determine if it is substantive. This guidance was adopted effective October 1, 2010. The adoption of this guidance did not have a material impact on our consolidated financial statements.

Organization and Basis of Presentation (Policies)

9 Months Ended

Jun. 30, 2012

Organization and Basis of Presentation [Abstract]

Nature of Business and Going Concern

Arrowhead Research Corporation is a nanomedicine company developing innovative therapies at the interface of biology and nanoengineering to cure disease and improve human health. Arrowhead has one of the most advanced and broadest technology platforms for therapeutics based on RNA interference (RNAi), including access to several different RNAi delivery systems and small interfering RNA (siRNA) structures in commercial development for RNAi therapeutics. This broad technology platform enables optimization of siRNA therapeutic candidates for delivery based on siRNA chemistry, tissue type, disease state, target gene and siRNA type and chemistry on a target-by-target basis. Through its acquisition of Alvos Therapeutics, Arrowhead has access to a large platform of proprietary human-derived homing peptides and the method for their discovery. These targeting peptide sequences can be linked to our siRNA delivery vehicles as well as to traditional small molecule drugs to preferentially shuttle them into target cells. Arrowhead is leveraging its in-house R&D expertise and capabilities, as well as a broad intellectual property portfolio for RNAi therapeutics, and RNAi and peptide delivery vehicles and targeting methods to seek development partnerships with other pharmaceutical and biotech companies committed to bringing RNAi therapeutics to market, as well as continuing the preclinical and clinical development of its own clinical candidates. Arrowhead’s non-RNAi development programs include a unique therapeutic candidate that shows promise in pre-clinical studies for the potential treatment of obesity and advanced bioactive materials for the regeneration of injured tissues.

Arrowhead operates a wholly-owned subsidiary, Arrowhead Madison Inc., which operates a lab facility in Madison, Wisconsin, supporting the company’s initiatives including the development of RNAi therapeutics. In addition to its wholly owned subsidiaries, Arrowhead Madison and Alvos Therapeutics, Arrowhead operates two majority-owned subsidiaries, Calando, a leader in delivering small interfering RNAs for gene silencing, and Ablaris, an anti-obesity therapeutics company, and has minority investments in Nanotope, a regenerative medicine company and Leonardo, a multistage drug delivery company.

Liquidity

Liquidity

Arrowhead has historically financed its operations through the sale of securities of Arrowhead and its Subsidiaries. Development activities have required significant capital investment since the Company’s inception and we expect our current portfolio companies to continue to require cash investment in fiscal 2012 and beyond to continue development.

At June 30, 2012, the Company had $2.3 million in cash to fund operations. During the nine months ended June 30, 2012, the Company’s cash position decreased by $5.2 million. The Company received cash from the issuance of equity of $5.4 million, cash from the sale of its holdings of stock in Wisepower Co. Ltd of $0.5 million, and cash collections from revenue of $0.2 million. The company had cash outflow of $10.6 million related to its continuing operating activities and capital expenditures of $0.4 million.

On August 13, 2012, the Company had received firm commitments for 2.3 million units at a price of $2.76 per unit in a registered offering to institutional and individual investors. Each unit consisted on one share of Arrowhead Common Stock and a warrant to purchase 0.75 share of Common Stock exercisable at $3.25 per share. Gross proceeds from the offering are expected to be approximately $6.2 million, with net proceeds of approximately $5.8 million after deducting commissions and fees.

As a result of the sale of the Company’s subsidiary, Unidym, in January 2011, the Company received $2.5 million in stock of the acquirer, Wisepower Co. Ltd. (“Wisepower”) and a $2.5 million convertible bond from Wisepower, of which approximately $200,000 is owed to a third party who was a minority investor in Unidym. During the quarter ended December 31, 2011, the Company sold its remaining stock in Wisepower. The convertible bond has a face value of $2.5 million, and is convertible into Wisepower common stock at a price of $2.00 per share. The bond can be redeemed for cash on January 17, 2013, and at which time could represent an additional source of liquidity for the company. The Company had Subscriptions Receivable of $1.0 million at June 30, 2012, which are expected to be collected over the next several months. In September 2011, the Company entered into an equity line facility whereby it has the ability to draw capital up to $15 million. Through June 30, 2012, the Company has drawn approximately $1 million from this facility and has issued 181,042 shares of common stock; the Company expects to draw upon the facility from time to time, depending on cash needs and market conditions.

On October 21, 2011, Arrowhead completed the acquisition of certain RNAi assets from Hoffmann-La Roche Inc. and F. Hoffmann-La Roche Ltd., including intellectual property and a research and development facility in Madison, Wisconsin. At the time of the acquisition, the Madison facility had 41 employees. Due to the costs associated with maintaining and operating the facility, including personnel costs, rent, research and development expenses, and other costs, cash expenses have increased, and it is expected that the Company will incur higher cash expenses will continue during the remainder of fiscal 2012 and beyond, relative to periods prior to the acquisition, as the Company accelerates its preclinical and clinical development efforts.

Based upon the Company’s cash on hand, other sources of liquidity, as described above, and based upon the Company’s operating plan, the Company’s management anticipates that the Company will be able to satisfy the cash requirements of its operations through at least the next twelve months. The Company anticipates that further equity financings, and/or asset sales and license agreements will be necessary to continue to fund operations in the future.

Basis of Presentation and Principles of Consolidation

Basis of Presentation and Principles of Consolidation

The accompanying unaudited consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial information and in accordance with the instructions to Form 10-Q and Article 8 of Regulation S-X. Accordingly, the financial statements do not include all of the information and notes required by GAAP for complete financial statements. In the opinion of management, all adjustments, including normal recurring accruals, considered necessary for a fair presentation have been included. Interim results are not necessarily indicative of results for a full year. The September 30, 2011 balance sheet was derived from audited financial statements, but does not include all disclosures required by GAAP. This financial information should be read in conjunction with the consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K for the year ended September 30, 2011.

The consolidated financial statements of the Company include the accounts of Arrowhead and its wholly-owned and majority-owned Subsidiaries. Prior to April 2008, Arrowhead’s Subsidiaries included Insert Therapeutics, Inc. (“Insert”), which was merged with Calando in April 2008. The merged entity is majority-owned by Arrowhead and continues to operate under the name of Calando. Arrowhead sold its interests in Unidym and Tego in 2011 and 2009, respectively. Unidym and Tego results are included in the Income (Loss) from Discontinued Operations. Income (Loss) from Discontinued Operations also includes Aonex Technologies, Inc. (“Aonex”), sold in 2008 and Nanotechnica, Inc. (“Nanotechnica”), dissolved in 2005. All significant intercompany accounts and transactions are eliminated in consolidation, and noncontrolling interests are accounted for in the Company’s financial statements. Certain reclassifications have been made to prior period financial statements to conform to the current period presentation.

Use of Estimates

Use of Estimates

The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the amounts reported in the accompanying financial statements. Actual results could differ from those estimates.

Testing Goodwill for Impairment

In September 2011, the FASB issued ASU 2011-08, Testing Goodwill for Impairment (“ASU 2011-08”), which amends the guidance in ASC 350-20, Intangibles—Goodwill and Other – Goodwill. ASU 2011-08 provides entities with the option of performing a qualitative assessment before calculating the fair value of the reporting unit when testing goodwill for impairment. If the fair value of the reporting unit is determined, based on qualitative factors, to be more likely than not less than the carrying amount of the reporting unit, the entities are required to perform a two-step goodwill impairment test. ASU 2011-08 was effective for us beginning January 1, 2012. The adoption of ASU 2011-08 did not have a material effect on our consolidated financial statements or disclosures.

Fair Value Measurement

In May 2011, the Financial Accounting Standards Board (“FASB”) issued ASU 2011-04, Fair Value Measurement (“ASU 2011-04”), which amended ASC 820, Fair Value Measurements (“ASC 820”), providing a consistent definition and measurement of fair value, as well as similar disclosure requirements between U.S. GAAP and International Financial Reporting Standards. ASU 2011-04 changes certain fair value measurement principles, clarifies the application of existing fair value measurement and expands the disclosure requirements. ASU 2011-04 was effective for us beginning January 1, 2012. The adoption of ASU 2011-04 did not have a material effect on our consolidated financial statements or disclosures.

In January 2010, the FASB issued Accounting Standards Update ASU No. 2010-06, Fair Value Measurements and Disclosures (Topic 820) – Improving Disclosures about Fair Value Measurements. This guidance requires new disclosures related to recurring and nonrecurring fair value measurements. The guidance requires disclosure of transfers of assets and liabilities between Level 1 and Level 2 of the fair value measurement hierarchy, including the reasons and the timing of the transfers and information on purchases, sales, issuance, and settlements on a gross basis in the reconciliation of the assets and liabilities measured under Level 3 of the fair value measurement hierarchy. The adoption of this guidance is effective for interim and annual reporting periods beginning after December 15, 2009. We have adopted this guidance in the financial statements presented herein, which did not have a material impact on our consolidated financial position or results of operations.

Revenue Recognition

In June 2010, the FASB issued ASU No. 2010-17, Revenue Recognition—Milestone Method (Topic 605): Milestone Method of Revenue Recognition. This ASU codifies the consensus reached in EITF Issue No. 08-9, “Milestone Method of Revenue Recognition.” The amendments to the Codification provide guidance on defining a milestone and determining when it may be appropriate to apply the milestone method of revenue recognition for research or development transactions. Consideration that is contingent on achievement of a milestone in its entirety may be recognized as revenue in the period in which the milestone is achieved only if the milestone is judged to meet certain criteria to be considered substantive. Milestones should be considered substantive in their entirety and may not be bifurcated. An arrangement may contain both substantive and nonsubstantive milestones, and each milestone should be evaluated individually to determine if it is substantive. This guidance was adopted effective October 1, 2010. The adoption of this guidance did not have a material impact on our consolidated financial statements.

- Definition

Disclosure of accounting policy for reporting when there is a substantial doubt about an entity's ability to continue as a going concern for a reasonable period of time (generally a year from the balance sheet date). Disclose: (a) pertinent conditions and events giving rise to the assessment of substantial doubt about the entity's ability to continue as a going concern for a reasonable period of time, (b) the possible effects of such conditions and events, (c) management's evaluation of the significance of those conditions and events and any mitigating factors, (d) possible discontinuance of operations, (e) management's plans (including relevant prospective financial information), and (f) information about the recoverability or classification of recorded asset amounts or the amounts or classification of liabilities. If management's plans alleviate the substantial doubt about the entity's ability to continue as a going concern, disclosure of the principal conditions and events that initially raised the substantial doubt about the entity's ability to continue as a going concern would be expected to be considered. Disclose whether operations for the current or prior years generated sufficient cash to cover current obligations, whether waivers were obtained from creditors relating to the company's default under the provisions of debt agreements and possible effects of such conditions and events, such as: whether there is a possible need to obtain additional financing (debt or equity) or to liquidate certain holdings to offset future cash flow deficiencies. Disclose appropriate parent company information when parent is dependent upon remittances from subsidiaries to satisfy its obligations.

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- Definition

Disclosure of accounting policy for revenue recognition. If the entity has different policies for different types of revenue transactions, the policy for each material type of transaction is generally disclosed. If a sales transaction has multiple element arrangements (for example, delivery of multiple products, services or the rights to use assets) the disclosure may indicate the accounting policy for each unit of accounting as well as how units of accounting are determined and valued. The disclosure may encompass important judgment as to appropriateness of principles related to recognition of revenue. The disclosure also may indicate the entity's treatment of any unearned or deferred revenue that arises from the transaction.

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- Definition

Disclosure of accounting policy for the use of estimates in the preparation of financial statements in conformity with generally accepted accounting principles.

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