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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	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

Consolidated Balance Sheets - USD ($)	Sep. 30, 2014	Sep. 30, 2013
CURRENT ASSETS
Cash and cash equivalents	$ 132,510,610	$ 19,114,444
Trade receivable		75,000
Prepaid expenses	588,626	532,354
Other current assets	48,502	91,660
Short term investments	21,653,032	9,030,261
TOTAL CURRENT ASSETS	154,800,770	28,843,719
Property and equipment, net	3,872,753	3,513,235
Intangible assets, net	1,013,473	3,240,513
Investments	23,088,346	1,702,153
Other assets	41,414	30,011
TOTAL ASSETS	182,816,756	37,329,631
CURRENT LIABILITIES
Accounts payable	2,579,478	1,199,632
Accrued expenses	1,399,486	638,884
Accrued payroll and benefits	3,268,506	905,771
Deferred revenue	103,125	103,125
Derivative liabilities	4,173,943	4,096,363
Capital lease obligation	213,991	221,345
Notes payable	50,000	971,557
Other current liabilities	58,495	588,343
TOTAL CURRENT LIABILITIES	11,847,024	8,725,020
LONG-TERM LIABILITIES
Notes payable, net of current portion		50,000
Capital lease obligation, net of current portion	758,340	1,061,113
Contingent consideration obligations	3,970,931	1,595,273
Other non-current liabilities	255,206	163,436
TOTAL LONG-TERM LIABILITIES	4,984,477	2,869,822
Commitments and contingencies
Arrowhead Research Corporation stockholders' equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized; 18,300 and 9,900 shares issued and outstanding as of September 30, 2014 and September 30, 2013, respectively	18	10
Common stock, $0.001 par value; 145,000,000 shares authorized; 54,656,936 and 32,489,444 shares issued and outstanding as of September 30, 2014 and September 30, 2013, respectively	147,026	124,859
Additional paid-in capital	391,164,558	193,514,766
Accumulated deficit	(224,771,159)	(166,140,969)
Total Arrowhead Research Corporation stockholders' equity	166,540,443	27,498,666
Non-controlling interest	(555,188)	(1,763,877)
TOTAL STOCKHOLDERS’ EQUITY	165,985,255	25,734,789
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 182,816,756	$ 37,329,631

Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2014	Sep. 30, 2013
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	18,300	9,900
Preferred stock, shares outstanding	18,300	9,900
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	145,000,000	145,000,000
Common stock, shares issued	54,656,936	32,489,444
Common stock, shares outstanding	54,656,936	32,489,444

Consolidated Statements of Operations - USD ($)	12 Months Ended
Consolidated Statements of Operations - USD ($)	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Income Statement [Abstract]
REVENUE	$ 175,000	$ 290,266	$ 146,875
OPERATING EXPENSES
Research and development	23,138,050	8,705,627	5,391,463
Salaries and payroll-related costs	12,829,355	6,667,669	6,414,921
General and administrative expenses	5,894,008	3,488,864	6,439,323
Stock-based compensation	5,696,173	1,536,271	1,241,404
Depreciation and amortization	1,345,655	1,751,412	1,748,975
Impairment expense	2,172,387	1,308,047
Contingent consideration - Fair Value Adjustments	2,375,658	1,421,652
TOTAL OPERATING EXPENSES	53,451,286	24,879,542	21,236,086
OPERATING LOSS	(53,276,286)	(24,589,276)	(21,089,211)
OTHER INCOME (EXPENSE)
Equity in income (loss) of unconsolidated affiliates	(78,874)	(641,141)	(240,154)
Impairment on investment in unconsolidated affiliates			(1,642,775)
Gain on purchase of Roche Madison			1,576,107
Gain (loss) on sale of fixed assets, net	(58,878)	(76,388)	(1,079,377)
Realized and unrealized gain (loss) in marketable securities			(58,091)
Interest income (expense), net	645,493	(97,910)	35,966
Change in value of derivatives	(6,033,659)	(5,300,389)	386,892
Other income (expense)	82,092	(997,975)
TOTAL OTHER INCOME (EXPENSE)	(5,443,826)	(7,113,803)	(1,021,432)
LOSS FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	(58,720,112)	(31,703,079)	(22,110,643)
Provision for income taxes	(5,300)
LOSS FROM CONTINUING OPERATIONS	(58,725,412)	(31,703,079)	(22,110,643)
NET INCOME (LOSS) FROM DISCONTINUED OPERATIONS		(354)	(80)
NET LOSS	(58,725,412)	(31,703,433)	(22,110,723)
Net (gain) loss attributable to non-controlling interests	95,222	560,144	984,795
NET LOSS ATTRIBUTABLE TO ARROWHEAD	$ (58,630,190)	$ (31,143,289)	$ (21,125,928)
NET LOSS PER SHARE ATTRIBUTABLE TO ARROWHEAD	$ (1.25)	$ (1.30)	$ (1.90)
SHAREHOLDERS - BASIC & DILUTED:
Weighted average shares outstanding - basic and diluted	46,933,030	24,002,224	11,129,766

Consolidated Statement of Stockholders' Equity - USD ($)	Total	Equity Issued in Business Combination	Common stock issued @ $3.80	Common stock issued @ $3.70	Common stock issued @ $4.00	Common stock issued @ 6.23	Common stock issued @ $5.11	Common stock issued @ $2.76	Preferred stock issued at $1,000 per share	Issued To Calando Stockholders In Exchange For Calando S Shares	Common stock issued @ $4.49	Common stock issued @ $2.26	Common stock issued @ $2.12	Common stock issued @ $1.83	Common stock issued @ $5.86	Common stock issued @ $18.95	Common Stock Issued to Galloway	Preferred Stock	Preferred Stock Preferred stock issued at $1,000 per share	Common Stock	Common Stock Equity Issued in Business Combination	Common Stock Common stock issued @ $3.80	Common Stock Common stock issued @ $3.70	Common Stock Common stock issued @ $4.00	Common Stock Common stock issued @ 6.23	Common Stock Common stock issued @ $5.11	Common Stock Common stock issued @ $2.76	Common Stock Issued Under Committed Capital Agreement	Common Stock Common stock issued @ $4.49	Common Stock Common stock issued @ $2.26	Common Stock Common stock issued @ $2.12	Common Stock Common stock issued @ $1.83	Common Stock Common stock issued @ $5.86	Common Stock Common stock issued @ $18.95	Common Stock Common Stock Issued to Galloway	Additional Paid-in Capital	Additional Paid-in Capital Equity Issued in Business Combination	Additional Paid-in Capital Common stock issued @ $3.80	Additional Paid-in Capital Common stock issued @ $3.70	Additional Paid-in Capital Common stock issued @ $4.00	Additional Paid-in Capital Common stock issued @ 6.23	Additional Paid-in Capital Common stock issued @ $5.11	Additional Paid-in Capital Common stock issued @ $2.76	Additional Paid-in Capital Issued Under Committed Capital Agreement	Additional Paid-in Capital Preferred stock issued at $1,000 per share	Additional Paid-in Capital Common stock issued @ $4.49	Additional Paid-in Capital Common stock issued @ $2.26	Additional Paid-in Capital Common stock issued @ $2.12	Additional Paid-in Capital Common stock issued @ $1.83	Additional Paid-in Capital Common stock issued @ $5.86	Additional Paid-in Capital Common stock issued @ $18.95	Additional Paid-in Capital Common Stock Issued to Galloway	Subscriptions Receivable	Subscriptions Receivable Common stock issued @ $3.80	Subscriptions Receivable Common stock issued @ $2.76	Accumulated Deficit during Development Stage	Noncontrolling Interest	Noncontrolling Interest Issued To Calando Stockholders In Exchange For Calando S Shares
Beginning Balance Amount at Sep. 30, 2011	$ 12,564,167																			$ 86,422																$ 127,476,435																	$ (900,000)			$ (113,871,752)	$ (226,938)
Beginning Balance Shares at Sep. 30, 2011																				8,642,286
Exercise of warrants, Amount	50,406																			$ 16																50,390
Exercise of warrants																				15,511
Stock options exercised, Amount	23,833									$ 8,000										$ 45																23,788																						$ 8,000
Stock options exercised																				4,583
Stock-based compensation	1,241,404																																			1,241,404
Stock issuances		$ 6,147,830	$ 425,000	$ 2,247,750	$ 400,000	$ 500,001	$ 500,001	$ 5,796,240	$ 1,015,000										$ 1		$ 9,332	$ 1,382	$ 6,750	$ 1,000	$ 83	$ 98	$ 2,261	$ 689									$ 6,138,498	$ 523,618	$ 2,241,000	$ 399,000	$ 499,918	$ 499,903	$ 5,809,979	$ (689)	$ 1,014,999									$ (100,000)	$ (16,000)
Stock issuances, Shares																			1,015		1,217,159	138,158	675,000	100,000	83,211	97,831	2,260,869	68,926
Fractional shares redeemed in reverse stock split																				(131)
Preferred stock converted to common stock, Amount																		$ (1)		$ 276																(275)
Preferred stock converted to common stock, Shares																		(1,015)		275,782
Net loss	(22,110,723)																																																							(21,125,928)	(984,795)
Ending Balance Amount at Sep. 30, 2012	8,808,909																			$ 108,354																145,917,968																	(1,016,000)			(134,997,680)	(1,203,733)
Ending Balance Shares at Sep. 30, 2012																				13,579,185
Exercise of warrants, Amount	2,054,599																			$ 1,183																2,053,416
Exercise of warrants																				1,182,451
Stock options exercised, Amount	$ 2,579																			$ 1																2,578
Stock options exercised	675																			675
Stock-based compensation	$ 1,536,271																																			1,536,271
Subscription payment	16,000																																																				16,000
Subscription reversal, Amount																				$ (2,674)																(997,326)																	$ 1,000,000
Subscription reversal																				(267,444)
Stock issuances									9,900,000		$ 986,049	$ 3,816,468	$ 3,256,859	$ 25,459,499					$ 10										$ 240	$ 1,825	$ 1,667	$ 14,263													9,899,990	$ 985,809	$ 3,814,643	$ 3,255,192	$ 25,445,236
Stock issuances, Shares																			9,900										239,894	1,825,079	1,667,051	14,262,553
Net loss	(31,703,433)																																																							(31,143,289)	(560,144)
Ending Balance Amount at Sep. 30, 2013	25,734,789																	$ 10		$ 124,859																193,514,766																				(166,140,969)	(1,763,877)
Ending Balance Shares at Sep. 30, 2013																		9,900		32,489,444
Establish and settlements related to derivative liability	1,600,989																																			1,600,989
Exercise of warrants, Amount	10,148,044																			$ 2,911																10,145,133
Exercise of warrants																				2,911,919
Stock options exercised, Amount	$ 2,730,000																			$ 455																2,729,545
Stock options exercised	454,863																			454,863
Stock-based compensation	$ 5,696,173																																			5,696,173
Stock issuances									$ 46,000,000						$ 14,060,112	$ 112,581,559	$ 500,000		$ 46														$ 3,072	$ 6,325	$ 132										$ 45,999,954					$ 14,057,040	$ 112,575,234	$ 499,868
Stock issuances, Shares																			46,000														3,071,672	6,325,000	131,579
Preferred stock converted to common stock, Amount																		$ (38)		$ 9,272																(9,234)
Preferred stock converted to common stock, Shares																		(37,600)		9,272,459
Net loss	(58,725,412)																																																							(58,630,190)	(95,222)
Ending Balance Amount at Sep. 30, 2014	165,985,255																	$ 18		$ 147,026																391,164,558																				$ (224,771,159)	(555,188)
Ending Balance Shares at Sep. 30, 2014																		18,300		54,656,936
Establish and settlements related to derivative liability	5,956,079																																			$ 5,956,079
Deconsolidation of Calando Pharmaceuticals, Inc.	$ 1,303,911																																																								$ 1,303,911

Consolidated Statement of Stockholders' Equity (Parenthetical) - $ / shares	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Common stock issued @ $3.80
Common stock issued, price per share			$ 3.80
Common stock issued @ $3.70
Common stock issued, price per share			3.70
Common stock issued @ $4.00
Common stock issued, price per share			4.00
Common stock issued @ 6.23
Common stock issued, price per share			6.23
Common stock issued @ $5.11
Common stock issued, price per share			5.11
Common stock issued @ $2.76
Common stock issued, price per share			2.76
Preferred stock issued at $1,000 per share
Common stock issued, price per share	$ 1,000	$ 1,000	$ 1,000
Common stock issued @ $4.49
Common stock issued, price per share		4.49
Common stock issued @ $2.26
Common stock issued, price per share		2.26
Common stock issued @ $2.12
Common stock issued, price per share		2.12
Common stock issued @ $1.83
Common stock issued, price per share		$ 1.83
Common stock issued @ $5.86
Common stock issued, price per share	5.86
Common stock issued @ $18.95
Common stock issued, price per share	$ 18.95

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
Consolidated Statements of Cash Flows - USD ($)	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
CASH FLOWS FROM OPERATING ACTIVITIES OF CONTINUING OPERATIONS:
Net loss	$ (58,725,412)	$ (31,703,433)	$ (22,110,723)
Net (gain) loss attributable to non-controlling interests	95,222	560,144	984,795
NET LOSS ATTRIBUTABLE TO ARROWHEAD	(58,630,190)	(31,143,289)	(21,125,928)
(Income) loss from discontinued operations		354	80
Realized and unrealized (gain) loss on investments			58,091
Charge for bad debt allowance			2,497,300
(Gain) loss on purchase of Roche Madison			(1,576,107)
(Gain) loss on disposal of fixed assets	58,878	76,388	1,079,377
Change in value of derivatives	6,033,659	5,300,389	(386,892)
Contingent consideration - Fair Value Adjustments	2,375,658	1,421,652
Stock-based compensation	5,696,173	1,536,271	1,241,404
Depreciation and amortization	1,345,655	1,751,412	1,748,975
Amortization/accretion of note premiums/discounts, net	793,887	128,406	9,390
Gain on debt extinguishment	(84,721)
Non-cash gain in equity investment	(87,197)
Non-cash impairment expense	2,172,387	2,315,721	1,642,775
Equity in income (loss) of unconsolidated affiliates			240,154
Non-controlling interest	(95,222)	(560,144)	(984,795)
Changes in operating assets and liabilities:
Receivables	75,000	(65,625)	162,855
Other receivables	(25,867)	1,080	(938,179)
Prepaid expenses	(15,812)	44,713	(338,531)
Other assets	(13,287)	(1,811)	(30,600)
Accounts payable	1,412,275	321,647	291,876
Accrued expenses	3,478,094	27,920	186,369
Other liabilities	94,257	(187,910)	882,296
NET CASH USED IN OPERATING ACTIVITIES OF CONTINUING OPERATIONS	(35,416,373)	(19,032,826)	(15,340,090)
CASH FLOWS FROM INVESTING ACTIVITIES OF CONTINUING OPERATIONS:
Purchases of property and equipment	(1,717,362)	(296,880)	(479,710)
Proceeds from sale of fixed assets	10,000	89,505	290,312
Purchase of marketable securities	(46,365,528)	(10,732,571)
Proceeds from sale of marketable securities	11,591,120	1,419,079	509,009
Cash transferred in acquisitions/divestitures			121,033
NET CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES OF CONTINUING OPERATIONS	(36,481,770)	(9,520,867)	440,644
CASH FLOWS FROM FINANCING ACTIVITIES OF CONTINUING OPERATIONS:
Principal payments on capital leases	(225,406)	(214,801)	(196,606)
Proceeds from issuance of common stock and preferred stock, net	172,641,671	42,448,826	10,883,992
Proceeds from the exercise of warrants and stock options	12,878,044	2,057,178	74,239
Proceeds from sale of stock in subsidiary			8,000
NET CASH PROVIDED BY FINANCING ACTIVITIES OF CONTINUING OPERATIONS	185,294,309	44,291,203	10,769,625
Cash flows from discontinued operations:
Operating cash flows		(354)	(280)
Investing cash flows	0	0	0
Financing cash flows	0	0	0
Net cash provided by (used in) discontinued operations:		(354)	(280)
NET INCREASE (DECREASE) IN CASH	113,396,166	15,737,156	(4,130,101)
CASH AT BEGINNING OF PERIOD	19,114,444	3,377,288	7,507,389
CASH AT END OF PERIOD	132,510,610	19,114,444	3,377,288
Supplementary disclosures:
Interest paid	$ 25,635	$ 42,044	$ 42,269

Consolidated Statements of Cash Flows (Parenthetical) - USD ($)	1 Months Ended
	Oct. 21, 2012	Feb. 18, 2014
Roche Madison Inc
Common stock, shares issued	239,894
Liability settlement	$ 986,049
Galloway Limited
Common stock, shares issued		131,579
Common stock value		$ 500,000

Organization and Significant Accounting Policies	12 Months Ended
Organization and Significant Accounting Policies	Sep. 30, 2014
Accounting Policies [Abstract]
Organization and Significant Accounting Policies	NOTE 1. ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES Nature of Business Arrowhead Research develops novel drugs to treat intractable diseases by silencing the genes that cause them. Using the broadest portfolio of RNA chemistries and efficient modes of delivery, Arrowhead therapies trigger the RNA interference mechanism to induce rapid, deep and durable knockdown of target genes. Arrowhead’s most advanced drug candidate in clinical development is ARC-520, which is designed to treat chronic hepatitis B infection by inhibiting the production of all HBV gene products. The goal is to reverse the immune suppression that prevents the body from controlling the virus and clearing the disease. Arrowhead’s second clinical candidate is ARC-AAT, a treatment for a rare liver disease associated with a genetic disorder that causes alpha-1 antitrypsin deficiency. Liquidity Historically, the Company’s primary source of financing has been through the sale of securities of Arrowhead Research Corp. Research and development activities have required significant capital investment since the Company’s inception and we expect our operations to continue to require cash investment in fiscal 2015 and beyond as the Company continues its research and development efforts, as well as clinical trials, and related drug manufacturing. At September 30, 2014, the Company had $132.5 million in cash to fund operations. In addition to its cash resources, the Company has invested excess cash in investment grade commercial bonds maturing in less than 2 years. These bonds provide a source of liquidity, although the Company plans to hold them until maturity. At September 30, 2014, the Company had invested $44.7 million in these bonds. During the year ended September 30, 2014, the Company’s cash position increased by $113.4 million which was the result of the receipt of cash from the issuance of equity of $172.6 million and cash from the exercise of warrants and options of $12.9 million, partially offset by cash outflows of $35.4 million related to continuing operating activities, net cash invested in fixed income investments of $34.8 million, and capital expenditures of $1.7 million. Summary of Significant Accounting Policies Principles of Consolidation— The consolidated financial statements include the accounts of Arrowhead and its Subsidiaries. Arrowhead’s primary operating subsidiary is Arrowhead Madison, which is located in Madison, Wisconsin, where the Company’s research and development facilities are located. All significant intercompany accounts and transactions are eliminated in consolidation, and noncontrolling interests are accounted for in the Company’s financial statements. Basis of Presentation and Use of Estimates—The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could materially differ from those estimates. Additionally, certain reclassifications have been made to prior period financial statements to conform to the current period presentation. Cash and Cash Equivalents—The Company considers all liquid debt instruments purchased with a maturity of three months or less to be cash equivalents. The Company had no restricted cash at September 30, 2014 and 2013, respectively. Concentration of Credit Risk—The Company maintains bank accounts for its operations at two financial institutions. These accounts are insured by the Federal Deposit Insurance Corporation (FDIC) for up to $250,000 per account. Management believes the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which these deposits are held. Investments—the Company may invest excess cash balances in short-term and long-term marketable debt securities. Investments may consist of certificates of deposits, money market accounts, government-sponsored enterprise securities, corporate bonds and/or commercial paper. The Company accounts for its investment in marketable securities in accordance with FASB ASC 320, Investments – Debt and Equity Securities. This statement requires certain securities to be classified into three categories: Held-to-maturity—Debt securities that the entity has the positive intent and ability to hold to maturity are reported at amortized cost. Trading Securities—Debt and equity securities that are bought and held primarily for the purpose of selling in the near term are reported at fair value, with unrealized gains and losses included in earnings. Available-for-Sale—Debt and equity securities not classified as either securities held-to-maturity or trading securities are reported at fair value with unrealized gains or losses excluded from earnings and reported as a separate component of shareholders’ equity. The Company classifies its investments in marketable debt securities based on the facts and circumstances present at the time of purchase of the securities. At September 30, 2014, the Company classified all of its investments as held-to-maturity. Held-to-maturity investments are measured and recorded at amortized cost on the Company’s Consolidated Balance Sheet. Discounts and premiums to par value of the debt securities are amortized to interest income/expense over the term of the security. No gains or losses on investment securities are realized until they are sold or a decline in fair value is determined to be other-than-temporary. Property and Equipment—Property and equipment are recorded at cost, which may equal fair market value in the case of property and equipment acquired in conjunction with a business acquisition. Depreciation of property and equipment is recorded using the straight-line method over the respective useful lives of the assets ranging from three to seven years. Leasehold improvements are amortized over the lesser of the expected useful life or the remaining lease term. Long-lived assets, including property and equipment, are reviewed for impairment whenever events or circumstances indicate that the carrying amount of these assets may not be recoverable. Intangible Assets Subject to Amortization—At September 30, 2014, intangible assets subject to amortization include certain license agreements. Intangible assets subject to amortization are reviewed for impairment whenever events or circumstances indicate that the carrying amount of these assets may not be recoverable. In-Process Research & Development (IPR&D)—IPR&D assets represent capitalized on-going research projects that Arrowhead acquired through business combinations. Such assets are initially measured at their acquisition date fair values. The amounts capitalized are being accounted for as indefinite-lived intangible assets, subject to impairment testing until completion or abandonment of R&D efforts associated with the project. Upon successful completion of a project, Arrowhead will make a determination as to the then remaining useful life of the intangible asset and begin amortization. Based on ASC 350 – Intangibles, Goodwill and Other, Arrowhead tests its indefinite-lived assets for impairment at least annually, through a two-step process. The first step is a qualitative assessment to determine if it is more likely than not that the indefinite lived assets are impaired. Arrowhead considers relevant events and circumstances that could affect the inputs used to determine the fair value of the intangible assets. If the qualitative assessment indicates that it is more likely than not that the intangible assets is impaired, a second step is performed which is a quantitative test to determine the fair value of the intangible asset. If the carrying amount of the intangible assets exceeds its fair value, an impairment loss is recorded in the amount of that excess. If circumstances determine that it is appropriate, the Company may also elect to bypass step one, and proceed directly to the second step. Contingent Consideration - The consideration for our acquisitions often includes future payments that are contingent upon the occurrence of a particular event. For example, milestone payments might be based on the achievement of various regulatory approvals or future sales milestones, and royalty payments might be based on drug product sales levels. We record a contingent consideration obligation for such contingent payments at fair value on the acquisition date. We estimate the fair value of contingent consideration obligations through valuation models designed to estimate the probability of the occurrence of such contingent payments based on various assumptions and incorporating estimated success rates. Estimated payments are discounted using present value techniques to arrive at estimated fair value at the balance sheet date. We revalue these contingent consideration obligations each reporting period. Changes in the fair value of our contingent consideration obligations are recognized within our Consolidated Statement of Operations. Changes in the fair value of the contingent consideration obligations can result from changes to one or multiple inputs, including adjustments to the discount rates, changes in the amount or timing of expected expenditures associated with product development, changes in the amount or timing of cash flows from products upon commercialization, changes in the assumed achievement or timing of any development milestones, changes in the probability of certain clinical events and changes in the assumed probability associated with regulatory approval. These fair value measurements are based on significant inputs not observable in the market. Significant judgment is employed in determining the appropriateness of these assumptions as of the acquisition date and for each subsequent period. Accordingly, changes in assumptions could have a material impact on the amount of contingent consideration expense we record in any given period. Noncontrolling Interests in Majority-Owned Subsidiaries—Operating losses applicable to majority-owned Ablaris, Calando (prior to its deconsolidation), and Unidym (prior to its disposal) have periodically exceeded the noncontrolling interests in the equity capital of either Subsidiary. Such excess losses applicable to the noncontrolling interests have been and are borne by the Company as there is no obligation of the noncontrolling interests to fund any losses in excess of their original investment. There is also no obligation or commitment on the part of the Company to fund operating losses of any Subsidiary whether wholly-owned or majority-owned. The Company allocates the noncontrolling interest’s share of net loss in excess of the noncontrolling interest’s initial investment in accordance with FASB ASC 810-10. When there is a change in the Company’s proportionate share of a Subsidiary resulting from additional equity transactions in a Subsidiary, the change is accounted for as an equity transaction in consolidation. To the extent that the increase in the calculated value of the Company’s interest in the equity of the Subsidiary exceeds the Company’s investment in the offering, that increase in value is referred to as the Company’s “increase in its proportionate share of the Subsidiary’s equity” and the amount is recorded as an increase in the Company’s Additional Paid-in Capital. Revenue Recognition—Revenue from license fees are recorded when persuasive evidence of an arrangement exists, title has passed or services have been rendered, a price is fixed and determinable, and collection is reasonably assured. We may generate revenue from product sales, technology licenses, collaborative research and development arrangements, and research grants. Revenue under technology licenses and collaborative agreements typically consists of nonrefundable and/or guaranteed technology license fees, collaborative research funding and various milestone and future product royalty or profit-sharing payments. Revenue associated with research and development funding payments under collaborative agreements is recognized ratably over the relevant periods specified in the agreement, generally the research and development period. Revenue from up-front license fees, milestones and product royalties are recognized as earned based on the completion of the milestones and product sales, as defined in the respective agreements. Payments received in advance of recognition as revenue are recorded as deferred revenue. Allowance for Doubtful Accounts—The Company accrues an allowance for doubtful accounts based on estimates of uncollectible revenues by analyzing historical collections, accounts receivable aging and other factors. Accounts receivable are written off when all collection attempts have failed. Research and Development—Costs and expenses that can be clearly identified as research and development are charged to expense as incurred in accordance with FASB ASC 730-10. Included in research and development costs are operating costs, facilities, supplies, external services, clinical trial and manufacturing costs, and overhead directly related to the Company’s research and development operations, as well as costs to acquire technology licenses. Earnings (Loss) per Share—Basic earnings (loss) per share is computed using the weighted-average number of common shares outstanding during the period. Diluted earnings (loss) per share are computed using the weighted-average number of common shares and dilutive potential common shares outstanding during the period. Dilutive potential common shares primarily consist of stock options and restricted stock units issued to employees and warrants to purchase Common Stock of the Company. All outstanding stock options, restricted stock units and warrants for the years ended September 30, 2014, 2013 and 2012 have been excluded from the calculation of Diluted earnings (loss) per share due to their anti-dilutive effect. Stock-Based Compensation—The Company accounts for share-based compensation arrangements in accordance with FASB ASC 718, which requires the measurement and recognition of compensation expense for all share-based payment awards to be based on estimated fair values. We use the Black-Scholes option valuation model to estimate the fair value of our stock options at the date of grant. The Black-Scholes option valuation model requires the input of subjective assumptions to calculate the value of stock options. We use historical data among other information to estimate the expected price volatility and the expected forfeiture rate. The fair value of restricted stock units granted is based upon the quoted closing market price per share on the date of grant, adjusted for assumed forfeitures. Expense for stock options and restricted stock units is recognized over the requisite service period. Derivative Assets and Liabilities - We account for warrants and other derivative financial instruments as either equity or assets/liabilities based upon the characteristics and provisions of each instrument. Warrants classified as equity are recorded as additional paid-in capital on our Consolidated Balance Sheet and no further adjustments to their valuation are made. Some of our warrants were determined to be ineligible for equity classification because of provisions that may result in an adjustment to their exercise price. Warrants classified as derivative liabilities and other derivative financial instruments that require separate accounting as assets or liabilities are recorded on our Consolidated Balance Sheet at their fair value on the date of issuance and are revalued on each subsequent balance sheet date until such instruments are exercised or expire, with any changes in the fair value between reporting periods recorded as other income or expense. We estimate the fair value of these assets/liabilities using option pricing models that are based on the individual characteristics of the warrants or instruments on the valuation date, as well as assumptions for expected volatility, expected life and risk-free interest rate. Income Taxes—The Company accounts for income taxes under the liability method, which requires the recognition of deferred income tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Under this method, deferred income taxes are recognized for the tax consequences in future years of differences between the tax bases of assets and liabilities and their financial reporting amounts at each period end based on enacted tax laws and statutory tax rates applicable to the periods in which the differences are expected to affect taxable income. Valuation allowances are established, when necessary, to reduce deferred income tax assets to the amount expected to be realized. The provision for income taxes, if any, represents the tax payable for the period and the change in deferred income tax assets and liabilities during the period. Recently Issued Accounting Standards In August 2014, the FASB issued ASU 2014-15, Presentation of Financial Statements – Going Concern (Topic 915): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern, which states that in connection with preparing financial statements for each annual and interim reporting period, an entity’s management should evaluate whether there are conditions or events, considered in the aggregate, that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date that the financial statements are issued (or within one year after the date that the financial statements are available to be issued when applicable). The adoption of this update did not have a material effect on our financial statements. In June 2014, the FASB issued ASU 2014-10, Development Stage Entities (Topic 915): Elimination of Certain Financial Reporting Requirements, Including an Amendment to Variable Interest Entities Guidance, which eliminates the distinction and separate requirements for development stage entities and other reporting entities under U.S. GAAP. Specifically the amendment eliminates the requirement for development stage entities to 1) present inception-to-date information in the statements of income, cash flow and shareholders’ equity, 2) label the financial statements as those of a development stage entity, 3) disclose a description of the development stage activities in which the entity is engaged and 4) disclose the first year in which the entity is no longer a development stage entity that in prior years it had been in the development stage. ASU 2014-10 is effective for fiscal years beginning after December 15, 2014 with early adoption permitted. The Company has adopted ASU 2014-10 effectively beginning with the filing of our Form 10-Q for period ended June 30, 2014. In May 2014, the FASB issued ASU No. 2014-09 Revenue from Contracts with Customers (Topic 606), which will supersede nearly all existing revenue recognition guidance under GAAP. ASU No. 2014-09 provides that an entity recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This update also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments, and assets recognized from costs incurred to obtain or fulfill a contract. ASU No. 2014-09 allows for either full retrospective or modified retrospective adoption and will become effective for the Company in the first quarter of 2018. The Company is evaluating the potential effects of the adoption of this update on its financial statements. In July 2013, the FASB issued ASU 2013-11, Income Taxes (Topic 740): Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists, which eliminates diversity in practice for the presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss or a tax credit carryforward is available to reduce the taxable income or tax payable that would result from disallowance of a tax position. ASU 2013-11 affects only the presentation of such amounts in an entity’s balance sheet and is effective for fiscal years beginning after December 15, 2013 and interim periods within those years. Early adoption is permitted. The adoption of this update did not have a material effect on our financial statements. In July 2012, the FASB issued ASU 2012-02, Testing Indefinite-Lived Intangible Assets for Impairment, which amended the guidance in ASU 2011-08 to simplify the testing of indefinite-lived intangible assets other than goodwill for impairment. ASU 2012-02 becomes effective for annual and interim impairment tests performed for fiscal years beginning on or after September 15, 2012 and earlier adoption is permitted. We adopted this standard in the third quarter of fiscal year 2012. The adoption of this update did not have a material effect on our financial statements.

Property and Equipment

12 Months Ended

Sep. 30, 2014

Property Plant And Equipment [Abstract]

Property and Equipment

NOTE 2. PROPERTY AND EQUIPMENT

The following table summarizes our major classes of property and equipment:


	September 30, 2014			September 30, 2013
Computers, office equipment and furniture	$	334,162		$	323,376
Research equipment		4,614,176			3,452,013
Software		69,623			69,623
Leasehold improvements		3,045,022			2,749,409
Total gross fixed assets		8,062,983			6,594,421
Less: Accumulated depreciation and amortization		(4,190,230	)		(3,081,186	)
Property and equipment, net	$	3,872,753		$	3,513,235

Investments

12 Months Ended

Sep. 30, 2014

Investments All Other Investments [Abstract]

Investments

NOTE 3. INVESTMENTS

The Company invests its excess cash balances in short-term and long-term debt securities. Investments at September 30, 2014 consisted of corporate bonds with maturities remaining of less than two years at the time of purchase. The Company may also invest excess cash balances in certificates of deposit, money market accounts, US Treasuries, US government agency obligations, corporate debt securities, and/or commercial paper. The Company accounts for its investments in accordance with FASB ASC 320, Investments – Debt and Equity Securities. At September 30, 2014, all investments were classified as held-to-maturity securities.

The following tables summarize the Company’s short and long-term investments as of September 30, 2014 and 2013, respectively:

	As of September 30, 2014
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Commercial notes (due within one year)	$	21,653,032	$	—	$	(189,830	)	$	21,463,202
Commercial notes (due after one year through two years)	$	23,088,346		—	$	(217,693	)	$	22,870,653
Total	$	44,741,378	$	—	$	(407,523	)	$	44,333,855

	As of September 30, 2013
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Commercial notes (due within one year)	$	9,030,261	$	7,500	$	(39,281	)	$	8,998,480
Commercial notes (due after one year through two years)	$	1,702,153		—	$	(2,362	)	$	1,699,791
Total	$	10,732,414	$	7,500	$	(41,643	)	$	10,698,271

Unrealized gains and losses are calculated as the difference between the fair value of a particular debt instrument as compared to its amortized cost. The Company’s debt instruments at September 30, 2014 consist of investment grade corporate bonds. There are many factors which can affect the fair value of a corporate bond, including general interest rates, prevailing inflation expectations, investors’ general appetite for risk, perceptions on the financial health of the bond issuers, and other factors. In general, the bonds we purchase have remaining maturities of less than two years, and small changes in economic factors have a lesser impact on the fair value of our bonds, as compared to, for example, bonds with longer maturities remaining. Given the current low interest rate environment, most bonds purchased by the Company have a coupon rate higher than the prevailing interest rate, and thus the bonds are purchased at a premium to par value. As these bonds near maturity, the fair value of each bond will naturally converge toward par value. The amortized cost of the bonds we hold will also converge toward par value, but more so based on the timing of coupon payments. Accordingly, it is not uncommon to report unrealized losses on bonds purchased at a premium to par, and since the Company expects to hold these bonds to maturity, these losses are not expected to be realized.

Acquisitions	12 Months Ended
Acquisitions	Sep. 30, 2014
Business Combinations [Abstract]
Acquisitions	NOTE 4. ACQUISITIONS Roche Madison On October 21, 2011, the Company entered into a Stock and Asset Purchase Agreement (the “RNAi Purchase Agreement”) with Hoffmann-La Roche Inc. and F Hoffmann-La Roche Ltd (collectively, “Roche”), pursuant to which the Company purchased from Roche (i) all of the outstanding common stock of Roche Madison Inc. (“Roche Madison”, now “Arrowhead Madison”) and (ii) the intellectual property rights then held by Roche related to its RNAi business and identified in the RNAi Purchase Agreement (the “Transaction”). In consideration for the purchase of Roche Madison and the Roche RNAi assets, the Company issued to Roche a promissory note with a principal value of $50,000 and 1,288,158 shares of Common Stock. Pursuant to the RNAi Purchase Agreement, Roche has a right of first negotiation on certain product candidates developed by the Company and its affiliates relating to the purchased assets. If the Company proposes to out-license or enters into substantive negotiations to out-license, any Clinical Candidate or Existing Candidate (as such terms are defined in the RNAi Purchase Agreement), the Company must give notice of the Candidate it proposes to out-license and negotiate exclusively and in good faith with Roche for 90 days regarding the applicable out-license. This right of first negotiation applies to all Existing Candidates (as defined in the RNAi Purchase Agreement) and the first five Clinical Candidates for which the Company delivers notice to Roche and subsequently enters into an out-license. In addition to the consideration paid by the Company as per the closing terms, the Company is obligated to make certain royalty and milestone payments to Roche upon the occurrence of certain events. For certain product candidates that are developed by the Company that are covered by a valid claim by the patent rights transferred in the Transaction for which the Company and Roche do not enter into a licensing arrangement, the Company will be obligated to pay a 3% royalty on Net Sales (as defined in the RNAi Purchase Agreement), provided that the royalty rate may be reduced or offset in certain circumstances. The obligation to pay royalties on such candidates will last until the later of (i) the expiration of the last to expire patent right related to such product candidate that was transferred in the Transaction and (ii) ten years after the first commercial sale of such product candidate. The Company will also be obligated to make cash payments to Roche upon the achievement of various milestones for certain clinical candidates, for which the Company and Roche do not enter into a licensing arrangement, including the first regulatory approval in certain jurisdictions, and upon certain annual sales milestones for candidates that receive regulatory approval. The potential payments range from $2,500,000 to $6,000,000 per milestone. At the time of acquisition, the Company’s estimate of future payments for potential royalties and milestones had a net present value of $84,935 which was recorded as contingent consideration as a part of other noncurrent liabilities. Contingent consideration is calculated by modeling research and development activities for clinical candidates, forecasting timelines to market, and using “peak sales” estimate modeling, cash flows and potential milestone and royalty payments. The modeling assumes certain success rates, and discount factors related to riskiness of projects and the time value of money to calculate a net present value of future consideration payments to Roche. These estimates are based on many unknown variables that are difficult to estimate, and due to the extended process of drug development prior to marketing of drug candidates, the models must extend many years into the future. Such predictions are inherently uncertain. Each reporting period, the Company re-evaluates its contingent consideration, and if material, makes adjustments to the recorded liability. Any adjustment to the contingent consideration liability is reflected in the Company’s Statement of Operations. As of September 30, 2014, the contingent consideration liability had been increased to $4.0 million, which is recorded on the Company’s Consolidated Balance Sheets. During the years ended September 30, 2014 and 2013, the Company recorded increases in the value of the contingent consideration liability of $2.4 million and $1.4 million, respectively.

- Definition

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=25497992&loc=d3e1497-128463

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 4
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-URI http://asc.fasb.org/extlink&oid=25497992&loc=d3e1392-128463

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-Name Accounting Standards Codification
-Topic 805
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-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=25497992&loc=d3e1486-128463

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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

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+ Details

Intangible Assets

12 Months Ended

Sep. 30, 2014

Goodwill And Intangible Assets Disclosure [Abstract]

Intangible Assets

NOTE 5. INTANGIBLE ASSETS

Intangible assets consist of in-process research and development (IPR&D) not subject to amortization, and license agreement intangible assets subject to amortization, which were capitalized as a part of a business combination.

IPR&D represents projects that have not yet received regulatory approval and are required to be classified as indefinite assets until the successful completion or the abandonment of the associated R&D efforts. Accordingly, during the development period after the date of acquisition, these assets will not be amortized until approval is obtained in one or more jurisdictions which, individually or combined, are expected to generate a significant portion of the total revenue expected to be earned by an IPR&D project. At that time, we will determine the useful life of the asset, reclassify the asset out of IPR&D and begin amortization. If the associated R&D effort is abandoned the related IPR&D assets will likely be written off and we would record an impairment loss.

Intangible assets not subject to amortization include IPR&D capitalized as part of the business combinations from the acquisitions of Roche Madison and Alvos. We review amounts capitalized as IPR&D for impairment at least annually in the fourth quarter, and whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. In the event the carrying value of the assets is not expected to be recovered, the assets are written down to their estimated fair values. We continue to test our indefinite-lived IPR&D assets for potential impairment until the projects are completed or abandoned.

During the year ended September 30, 2014, the Company determined that the carrying value of the Alvos IPR&D may not be recoverable. The Company has had difficulty advancing the development of the Alvos technology, and has been unsuccessful in finding partners to license the technology. As such, and due to higher priority research programs, the Company has abandoned its efforts to further develop this technology. Based on these events and circumstances, Management has determined that the value of the Alvos IPR&D was fully impaired as of September 30, 2014, and the Company recorded an impairment charge of $2.2 million, which is presented as a part of operating expenses for the year ended September 30, 2014.

On August 5, 2013, Calando terminated a License Agreement with the California Institute of Technology (the “License”). The License provided Calando with exclusive rights to develop and commercialize therapeutics based on the linear cyclodextrin drug delivery technology invented at Caltech. The drug delivery technology platforms, Cyclosert^TM and RONDEL^TM, as well as the drug candidates IT-101 and CALAA-01, were developed based on the licensed technology. Calando was responsible to direct and pay for the prosecution of the patents and patent applications covered by the License and to progress the technology. In conjunction with a previous business acquisition, the patents covered by this license agreement had been capitalized, and had a net book value of $1.3 million at June 30, 2013. Management determined that the value of the patents was impaired as of June 30, 2013, and the Company recorded an impairment charge of $1.3 million, and is presented as a part of operating expenses for the year ended September 30, 2013.

Intangible assets subject to amortization include license agreements capitalized as part of a business combination from the acquisition of Roche Madison. The license agreements are being amortized over the estimated life remaining at the time of acquisition which was 4 years, and the accumulated amortization of the assets is approximately $161,500. Patents have been amortized over a period of three years to twenty years, however all patent assets were fully impaired during the year ended September 30, 2013. Amortization expense for the years ended September 30, 2014, 2013 and 2012 was $54,653, $236,009 and $293,964, respectively. The weighted average original amortization period is twelve years. Amortization expense is expected to be approximately $55,000 for fiscal year 2015, $13,000 in 2016, and zero thereafter.

The below table provides details on our intangible asset balances:

	Intangible assets not subject to amortization		Intangible assets subject to amortization		Total Intangible assets
Balance at September 30, 2012	$	3,117,322	$	1,667,247	$	4,784,569
Impairment		-		(1,308,047)		(1,308,047	)
Amortization		-		(236,009)		(236,009	)
Balance at September 30, 2013	$	3,117,322	$	123,191	$	3,240,513
Impairment		(2,172,387)		-		(2,172,387	)
Amortization		-		(54,653)		(54,653	)
Balance at September 30, 2014	$	944,935	$	68,538	$	1,013,473

Investment in Subsidiaries	12 Months Ended
Investment in Subsidiaries	Sep. 30, 2014
Investments All Other Investments [Abstract]
Investment in Subsidiaries	NOTE 6. INVESTMENT IN SUBSIDIARIES In addition to 100% ownership interest in Arrowhead Madison Inc., Arrowhead also maintains majority ownership in Ablaris Therapeutics, Inc. Ablaris Therapeutics, Inc. Ablaris was formed and began operations in fiscal 2011, based on the license of certain anti-obesity technology developed at the MD Anderson Cancer Center at the University of Texas. During fiscal 2011, Ablaris raised $2.9 million in cash, of which $1.3 million was invested by Arrowhead and $1.6 million was invested by outside investors, through the issuance of Ablaris Series A Preferred stock. As of September 30, 2014, Arrowhead owned 64% of the outstanding shares of Ablaris and 64% on a fully diluted basis. Calando Pharmaceuticals, Inc. Calando has ceased operations and terminated its technology license with the California Institute of Technology on which its siRNA therapeutic development efforts were based. Further, pursuant to an involuntary petition by an unpaid Noteholder, Calando is undergoing Chapter 7 bankruptcy proceedings. During the year ended September 30, 2014, Arrowhead deconsolidated Calando based on the fact that Calando is now subject to the control of the bankruptcy trustee in accordance with ASC 810. The deconsolidation of Calando resulted in an approximately $87,000 gain to the Company’s Consolidated Statement of Operations. As of September 30, 2014, Calando owed to Arrowhead $4.5 million under a series of 8% simple interest notes and advances. It is unlikely these notes will be repaid in full. The balance of the notes and advances has been fully reserved. As of September 30, 2014, Arrowhead owned 79% of the outstanding shares of Calando and 76% on a fully diluted basis. As a result of the ongoing bankruptcy proceeding for Calando, we do not expect our equity ownership to result in any return of capital as part of the liquidation of Calando.

Stockholders' Equity

12 Months Ended

Sep. 30, 2014

Equity [Abstract]

Stockholders' Equity

NOTE 7. STOCKHOLDERS’ EQUITY

At September 30, 2014, the Company had a total of 150,000,000 shares of capital stock authorized for issuance, consisting of 145,000,000 shares of Common Stock, par value $0.001, and 5,000,000 shares of Preferred Stock, par value $0.001.

At September 30, 2014, 54,656,936 shares of Common Stock were outstanding; 18,300 shares of Preferred Stock were outstanding, including 2,300 shares of Series B Preferred Stock, convertible into 1,256,831 shares of Common Stock, and 16,000 shares of Series C Preferred Stock, convertible into 2,730,375 shares of Common Stock. At September 30, 2014, 7,165,174 shares were reserved for issuance upon exercise of options or restricted stock units granted or available for grant under Arrowhead’s 2000 Stock Option Plan, 2004 Equity Incentive Plan, 2013 Incentive Plan, as well as for inducement grants made to new employees.

The Preferred Stock is convertible to Common Stock by its holder at its stated conversion price, though the Preferred Stock is not convertible to the extent the holder would beneficially own more than 9.99% of the number of Common Stock immediately after the conversion. The holders of Preferred Stock are eligible to vote with the Common Stock of the Company on an as-converted basis, but only to the extent they are eligible for conversion without exceeding the 9.99% ownership limitation. The Preferred Stock does not carry a coupon, but the Preferred Stock is entitled to receive dividends on a pari passu basis with Common Stock, when and if declared. In any liquidation or dissolution of the Company, the holders of Preferred Stock are entitled to participate in the distribution of the assets, to the extent legally available for distribution, on a pari passu basis with the Common Stock.

On October 21, 2011 and October 24, 2011, the Company entered into Subscription Agreements with certain accredited investors, pursuant to which the Company issued and sold an aggregate of 1,015 shares of Series A Preferred Convertible Stock, $0.001 par value per share (“Series A Preferred”), at a purchase price of $1,000 per share. The aggregate purchase price paid for the shares of Series A Preferred was $1,015,000. On February 16, 2012, upon approval by the Company’s shareholders, 1,015 shares of Series A Preferred, representing all shares of outstanding Series A Preferred, were converted to 275,782 shares of Common Stock.

On October 21, 2011, the Company entered into a Subscription Agreement with an accredited investor, pursuant to which the Company issued and sold an aggregate of 675,000 shares of Common Stock, $0.001 par value per share, at a purchase price of $3.70 per share. The aggregate purchase price paid by the purchaser for the shares of Common Stock is $2,497,500.

On August 10, 2012 the Company sold 2,260,869 units at a price of $2.76 per unit. Each unit consisted of one share of Common Stock and a warrant to purchase 0.75 shares of Common Stock at an exercise price of $3.25. Gross proceeds from the offering were $6.2 million excluding offering fees and expenses.

In December 2012, the Company sold 1,825,079 units at a price of $2.26 per unit. Each unit consisted of one share of Common Stock and a warrant to purchase 0.5 shares of Common Stock. Gross proceeds from the offering were $4.1 million excluding offering fees and expenses. The exercise price of these warrants was $1.83 as of September 30, 2014, and may decrease based on certain specified events. As a result, the Company determined these warrants were ineligible for equity classification. Refer to the Fair Value footnote for further discussion regarding these warrants.

In January 2013, the Company sold 1,667,051 units at a price of $2.12 per unit. Each unit consisted of one share of Common Stock and a warrant to purchase 0.5 shares of Common Stock. Gross proceeds from the offering were $3.5 million excluding offering fees and expenses. The exercise price of these warrants was $1.83 as of September 30, 2014, and may decrease based on certain specified events. As a result, the Company determined these warrants were ineligible for equity classification. Refer to the Fair Value footnote for further discussion regarding these warrants.

In May 2013, the Company sold 14.3 million shares of Common Stock at a price of $1.83 per share and 9,900 shares of Arrowhead Series B Preferred Stock at a price of $1,000 per share. The Series B Preferred Stock is convertible into Common Stock at a conversion price of $1.83. Gross proceeds were $36 million. No warrants were issued in the May 2013 financing.

On October 11, 2013, the Company sold 3,071,672 shares of Common Stock, at a price of $5.86 per share, and 46,000 shares of Series C Preferred Stock, at a price of $1,000 per share. The Series C Preferred Shares are convertible into shares of Common Stock at a conversion price of $5.86. The aggregate purchase price paid by the purchasers for the Common Stock and Preferred Shares was $64,000,000 and the Company received net proceeds of approximately $60,000,000, after advisory fees and offering expenses.

On February 24, 2014, the Company sold 6,325,000 shares of Common Stock, at a public offering price of $18.95 per share. Net proceeds were approximately $112.6 million after underwriting commissions and discounts and other offering expenses.

As of November 17, 2011, the Company effected a 1 for 10 reverse stock split. As a result of the reverse stock split, each ten shares of the Company’s Common Stock issued and outstanding immediately prior to the reverse stock split was combined into one share of Common Stock. Also, as a result of the reverse stock split, the per share exercise price, and the number of shares of Common Stock underlying Company stock options, warrants, and any Common Stock based equity grants outstanding immediately prior to the reverse stock split was proportionally adjusted, based on the one-for-ten split ratio, in accordance with the terms of such options, warrants or other Common Stock based equity grants, as the case may be. No fractional shares of Common Stock were issued in connection with the reverse split. Stockholders received a cash payment in lieu of any fractional shares. All share and per share amounts in these financial statements have been retrospectively adjusted to reflect the reverse stock split.

The following table summarizes information about warrants outstanding at September 30, 2014:

Exercise prices		Number of Warrants		Remaining Life in Years
$	70.60		94,897		2.6
$	5.00		413,825		0.9
$	5.09		269,912		0.2
$	1.38		24,324		1.2
$	4.16		1,000		2.2
$	3.25		334,347		1.9
$	2.12		75,000		3.2
$	1.83		277,284		3.2
Total warrants outstanding			1,490,589

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
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Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6521494

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21564-112644

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
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Reference 15: http://www.xbrl.org/2003/role/presentationRef
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Reference 16: http://www.xbrl.org/2003/role/presentationRef
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Reference 17: http://www.xbrl.org/2003/role/presentationRef
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Reference 18: http://www.xbrl.org/2003/role/presentationRef
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Reference 19: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Commitments and Contingencies

12 Months Ended

Sep. 30, 2014

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

NOTE 8. COMMITMENTS AND CONTINGENCIES

Leases

The Company leases office space for its corporate headquarters in Pasadena, California. In March 2014, the Company signed a lease addendum to expand its corporate headquarters, and the new space became available in September 2014. The leases for the expansion space and the current space will expire in September 2019. Rental costs, including the expansion space are approximately $23,000 per month, increasing approximately 3% annually.

The Company’s research facility in Madison, Wisconsin is leased through February 28, 2019. Monthly rental expense is approximately $25,000. Other monthly rental expenses include common area maintenance and real estate taxes totaling approximately $16,000 per month. Utilities costs are approximately $15,000 per month. Total monthly costs are approximately $75,000 per month, including monthly payments recorded under a capital lease of approximately $19,000.

Facility rent expense, related to continuing operations, for the years ended September 30, 2014, 2013 and 2012 was $554,000, $534,000 and $480,000, respectively.

As of September 30, 2014, future minimum lease payments due in fiscal years under capitalized leases are as follows:

2015	$	228,420
2016		228,420
2017		228,420
2018		228,420
2019		95,175
2020 and thereafter		-
Less interest		(36,524)
Principal		972,331
Less current portion		(213,991	)
Noncurrent portion	$	758,340

As of September 30, 2014, future minimum lease payments due in fiscal years under operating leases are as follows:

2015	$	580,306
2016		596,877
2017		613,664
2018		637,897
2019		459,633
2020 and thereafter		-
Total	$	2,888,377

Litigation

The Company, Christopher R. Anzalone, and Bruce D. Given have been named as defendants in putative securities class actions filed in the Central District of California regarding certain public statements in connection with the Company’s hepatitis B drug research. Two suits are currently pending: Wang v. Arrowhead Research Corp., et al., No. 2:14-cv-07890, filed October 10, 2014, and Eskinazi v. Arrowhead Research Corp., et al., No. 2:14-cv-07911, filed October 13, 2014 (collectively, the “Securities Claims”). Both cases are assigned to the Hon. Consuelo B. Marshall. Both plaintiffs bring claims under Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 and seek damages in an unspecified amount. Motions for appointment of lead plaintiff and lead counsel are due December 9, 2014, pursuant to the Private Securities Litigation Reform Act of 1995. On November 20, 2014, a putative stockholder derivative action was filed in United States District Court for the Central District of California, alleging breach of fiduciary duty by the Company’s Board of Directors in connection with the facts underlying the Securities Claims. The complaint, Weisman v. Anzalone et al., No. 2:14-cv-08982, seeks unspecified damages and attorneys’ fees.

The Company has been named as a defendant in a complaint filed by William Marsh Rice University (“Rice University”) in the District Court of Harris County, Texas relating to alleged breaches of a license agreement between Rice University and the Company’s former subsidiary, Unidym, Inc. The suit, captioned, William Marsh Rice University vs. Unidym, Inc. and Arrowhead Research Corporation, No. 2014-66088, was filed November 11, 2014. The plaintiff has alleged that the Company fraudulently induced Rice University to take certain actions with respect to Unidym’s license from Rice University and seeks injunctive relief, damages, including unspecified compensatory and punitive damages, and attorneys’ fees.

The Company believes it has a meritorious defense and intends to vigorously defend itself in each of the above matters. The Company makes provisions for liabilities when it is both probable that a liability has been incurred and the amount can be reasonably estimated. No such liability has been recorded related to these matters. The Company does not expect these matters to have any material effect on its Consolidated Financial Statements. With regard to legal fees, such as attorney fees related to these matters or any other legal matters, the Company’s accounting policy is to recognize such cost as incurred.

Purchase Commitments

In the normal course of business, we enter into various purchase commitments for the manufacture of drug components, toxicology studies, and for clinical studies. As of September 30, 2014, these future commitments were approximately $21.4 million, of which approximately $19.5 million is expected to be incurred in fiscal 2015, and $1.9 million is expected to be incurred beyond fiscal 2015.

Technology License Commitments

The Company has licensed from third parties the rights to use certain technologies that it uses in its research and development activities, as well as in any products the Company may develop using these licensed technologies. These agreements and other similar agreements often require milestone and royalty payments. Milestone payments, for example, may be required as the research and development process progresses through various stages of development, such as when clinical candidates enter or progress through clinical trials, upon NDA and upon certain sales level milestones. These milestone payments could amount to the mid to upper double digit millions of dollars. In certain agreements, the Company may be required to make mid to high single digit percentage royalty payments based on a percentage of the sales of the relevant products.

Stock-Based Compensation

12 Months Ended

Sep. 30, 2014

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

NOTE 9. STOCK-BASED COMPENSATION

Arrowhead has three plans that provide for equity-based compensation, collectively the “Plans”. Under the 2000 Stock Option Plan, 38,000 shares of Arrowhead’s Common Stock are reserved for issuance upon exercise of non-qualified stock options. No further grants can be made under the 2000 Stock Option Plan. The 2004 Equity Incentive Plan reserves 2,659,852 shares for the grant of stock options, stock appreciation rights, restricted stock awards and performance unit/share awards by the Board of Directors to employees, consultants and others. The 2013 Incentive Plan reserves 4,000,000 shares for the grant of stock options, stock appreciation rights, restricted stock awards and performance unit/share awards by the Board of Directors to employees, consultants and others. As of September 30, 2014, there were options and restricted stock units outstanding of 38,000, 2,563,518, and 1,292,000 shares of Common Stock under the 2000, 2004 and 2013 Plans, respectively. Also, as of September 30, 2014, there were 467,322 shares reserved for options and restricted stock units issued outside of equity compensation plans, as inducement grants to new employees. During the year ended September 30, 2014, no options or restricted stock units were granted under the 2004 Equity Incentive Plan, 1,324,000 options and restricted stock units were granted under the 2013 Incentive Plan, and 185,000 options and 40,000 restricted stock units were granted outside of the Plans as inducement stock options and restricted stock units to new employees.

The following tables summarize information about stock options:

	Number of Options Outstanding			Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Term		Aggregate Intrinsic Value
Balance At September 30, 2012		1,910,794			6.10
Granted		1,509,166			2.03
Cancelled		-			-
Exercised		(675	)		3.93
Balance At September 30, 2013		3,419,285			4.68
Granted		1,039,000			14.05
Cancelled		(152,582)			6.05
Exercised		(454,863)			6.00
Balance At September 30, 2014		3,850,840			6.99		8.1 years		$31,141,826
Exercisable At September 30, 2014		1,684,919			5.94		7.2 years		$15,518,772

Stock-based compensation expense related to stock options for the years ended September 30, 2014, 2013 and 2012 was $3,144,776, $1,536,271, and $1,241,404, respectively. There is no income tax benefit as the Company is currently operating at a loss and an actual income tax benefit may not be realized. For non-qualified stock options, the loss creates a timing difference, resulting in a deferred tax asset, which is fully reserved by a valuation allowance.

The fair value of the options granted by Arrowhead for the years ended September 30, 2014, 2013 and 2012 is estimated at $9,267,048, $2,843,575 and $4,091,117, respectively.

The intrinsic value of the options exercised during the years ended September 30, 2014, 2013 and 2012 was $4,360,850, $554, and $0, respectively.

As of September 30, 2014, the pre-tax compensation expense for all unvested stock options at Arrowhead in the amount of approximately $10,517,380 will be recognized in the Company’s results of operations over a weighted average period of 3.1 years.

The fair value of each stock option award is estimated on the date of grant using the Black-Scholes option pricing model. The Black-Scholes option valuation model was developed for use in estimating the fair value of traded options, which do not have vesting restrictions and are fully transferable. The determination of the fair value of each stock option is affected by our stock price on the date of grant, as well as assumptions regarding a number of highly complex and subjective variables. Because the Company’s employee stock options have characteristics significantly different from those of traded options, and because changes in the subjective input assumptions can materially affect the fair value estimate, in management’s opinion, the existing models do not necessarily provide a reliable single measure of the fair value of its employee stock options.

The assumptions used to value stock options are as follows:

	Year ended September 30,
	2014	2013	2012
Dividend yield	—	—	—
Risk-free interest rate	1.8% to 2.4%	0.7% to 2.3%	0.9% to 1.7%
Volatility	69%	69%	90% - 100%
Expected life (in years)	6.25 to 9.47	5.5 to 6.25	5.5 to 6.25
Weighted average grant date fair value per share of options granted	$8.92	$1.88	$3.32

The dividend yield is zero as the Company currently does not pay a dividend.

The risk-free interest rate is based on the U.S. Treasury bond.

Volatility is estimated based on volatility average of the Company’s Common Stock price.

Restricted Stock Units

Restricted Stock Units (RSUs) were granted under the Company’s 2013 Incentive Plan as well as inducement grants granted outside of the Plan. During the years ended September 30, 2014, 2013 and 2012 the Company issued 510,000, 0 and 0 restricted stock units to certain members of management and certain members of its Board of Directors, respectively. Of the restricted stock units granted, 470,000 were granted under the Company’s 2013 Incentive Plan and 40,000 were granted outside of the Plan as inducement grants to new employees. At vesting each RSU will be exchanged for one share of the Company’s Common Stock. The RSUs issued to management vest in equal annual installments over two to three years from the anniversaries of the date of grant. The RSUs issued to the members of the Board of Directors vest upon the one year anniversary of the date of grant.

The following table summarizes the activity of the Company’s Restricted Stock Units:

	Number of RSUs		Weighted- Average Grant Date Fair Value
Unvested at September 30, 2012		—	$	—
Granted		—		—
Vested		—		—
Forfeited		—		—
Unvested at September 30, 2013		—		—
Granted		510,000	$	14.58
Vested		—		—
Forfeited		—		—
Unvested at September 30, 2014		510,000	$	14.58

The Company recorded $2,551,397, $0 and $0 of expense relating to restricted stock units during the years ended September 30, 2014, 2013 and 2012, respectively, and such expense is included in stock-based compensation expense in the Company’s Consolidated Statement of Operations.

As of September 30, 2014, the pre-tax compensation expense for all unvested restricted stock units in the amount of approximately $4,913,516 will be recognized in the Company’s results of operations over a weighted average period of 1.5 years.

Fair Value Measurements

12 Months Ended

Sep. 30, 2014

Fair Value Disclosures [Abstract]

Fair Value Measurements

NOTE 10. FAIR VALUE MEASUREMENTS

The Company measures its financial assets and liabilities at fair value. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (i.e., exit price) in an orderly transaction between market participants at the measurement date. Additionally, the Company is required to provide disclosure and categorize assets and liabilities measured at fair value into one of three different levels depending on the assumptions (i.e., inputs) used in the valuation. Level 1 provides the most reliable measure of fair value while Level 3 generally requires significant management judgment. Financial assets and liabilities are classified in their entirety based on the lowest level of input significant to the fair value measurement. The fair value hierarchy is defined as follows:

Level 1—Valuations are based on unadjusted quoted prices in active markets for identical assets or liabilities.

Level 2—Valuations are based on quoted prices for similar assets or liabilities in active markets, or quoted prices in markets that are not active for which significant inputs are observable, either directly or indirectly.

Level 3—Valuations are based on prices or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement. Inputs reflect management’s best estimate of what market participants would use in valuing the asset or liability at the measurement date.

The following table summarizes fair value measurements at September 30, 2014 and September 30, 2013 for assets and liabilities measured at fair value on a recurring basis:

September 30, 2014:

	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	132,510,610	$	—	$	—	$	132,510,610
Derivative liabilities	$	—	$	—	$	4,173,943	$	4,173,943
Contingent consideration obligations related to acquisitions	$	—	$	—	$	3,970,931	$	3,970,931

September 30, 2013:

	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	19,114,444	$	—	$	—	$	19,114,444
Derivative liabilities	$	—	$	—	$	4,096,363	$	4,096,363
Contingent consideration obligations related to acquisitions	$	—	$	—	$	1,595,273	$	1,595,273

The Company invests its excess cash balances in short and long-term corporate bonds, generally with remaining maturities of less than two years. At September 30, 2014, the Company had short-term investments of $21.7 million, and long-term investments of $23.1 million, for a total of $44.7 million. The fair value of its investment at September 30, 2014 was $44.3 million. The Company expects to hold such investments until maturity, and thus unrealized gains and losses from the fluctuations in the fair value of the securities are not likely to be realized.

As part of an equity financing in June 2010, Arrowhead issued warrants to acquire up to 329,649 shares of Common Stock (the “2010 Warrants”), of which 24,324 warrants were outstanding at September 30, 2014. Similarly, as part of a financing in December 2012, Arrowhead issued warrants to acquire up to 912,543 shares of Common Stock (the “2012 Warrants”) of which 265,161 warrants were outstanding at September 30, 2014. Further, as part of a financing in January 2013, Arrowhead issued warrants to acquire up to 833,530 shares of Common Stock (the “2013 Warrants”) of which 12,123 warrants were outstanding at September 30, 2014 (collectively the “Warrants”). Each of the Warrants discussed above contains a mechanism to adjust the strike price upon the issuance of certain dilutive equity securities. If during the terms of the Warrants, the Company issues Common Stock at a price lower than the exercise price for the Warrants, the exercise price would be reduced to the amount equal to the issuance price of the Common Stock. As a result of these features, the Warrants are subject to derivative accounting as prescribed under ASC 815. Accordingly, the fair value of the Warrants on the date of issuance was estimated using an option pricing model and recorded on the Company’s Consolidated Balance Sheet as a derivative liability. The fair value of the Warrants is estimated at the end of each reporting period and the change in the fair value of the Warrants is recorded as a non-operating gain or loss as change in value of derivatives in the Company’s Consolidated Statement of Operations. During the years ended September 30, 2014, the Company recorded a non-cash loss from the change in fair value of the derivative liability of $5,821,796.

The assumptions used in valuing the derivative liability as of September 30, 2014 and 2013 were as follows:

2010 Warrants	September 30, 2014	September 30, 2013
Risk free interest rate	0.13%	0.33%
Expected life	1.2 Years	2.2 Years
Dividend yield	None	None
Volatility	69%	69%

2012 Warrants	September 30, 2014	September 30, 2013
Risk free interest rate	1.07%	1.39%
Expected life	3.2 Years	4.2 Years
Dividend yield	None	None
Volatility	69%	69%

2013 Warrants	September 30, 2014	September 30, 2013
Risk free interest rate	1.07%	1.39%
Expected life	3.3 Years	4.3 Years
Dividend yield	None	None
Volatility	69%	69%

The following is a reconciliation of the derivative liability related to these warrants for the years ended September 30, 2014 and 2013:

Value at September 30, 2012	$	626,195
Issuance of instruments		2,153,819
Change in value		5,066,591
Net settlements		(3,754,808	)
Value at September 30, 2013	$	4,091,797
Issuance of instruments		—
Change in value		5,821,796
Net settlements		(5,956,079)
Value at September 30, 2014	$	3,957,514

In conjunction with the financing of Ablaris in fiscal 2011, Arrowhead sold exchange rights to certain investors whereby the investors have the right to exchange their shares of Ablaris for a prescribed number of Arrowhead shares based upon a predefined ratio. The exchange rights have a seven-year term. During the first year, the exchange right allows the holder to exchange one Ablaris share for 0.06 Arrowhead shares. This ratio declines to 0.04 in the second year, 0.03 in the third year and 0.02 in the fourth year. In the fifth year and beyond the exchange ratio is 0.01. Exchange rights for 675,000 Ablaris shares were sold in fiscal 2011, and remain outstanding at September 30, 2014. The exchange rights are subject to derivative accounting as prescribed under ASC 815. Accordingly, the fair value of the exchange rights on the date of issuance was estimated using an option pricing model and recorded on the Company’s Consolidated Balance Sheet as a derivative liability. The fair value of the exchange rights is estimated at the end of each reporting period and the change in the fair value of the exchange rights is recorded as a nonoperating gain or loss in the Company’s Consolidated Statement of Operations. During the year ended September 30, 2014, the Company recorded a non-cash loss from the change in fair value of the derivative liability of $211,860.

The assumptions used in valuing the derivative liability as of September 30, 2014 and 2013 were as follows:

	September 30, 2014	September 30, 2013
Risk free interest rate	1.07%	1.39%
Expected life	3.3 Years	4.3 Years
Dividend yield	None	None
Volatility	100%	100%

The following is a reconciliation of the derivative liability related to these exchange rights for the years ended September 30, 2014 and 2013:

Value at September 30, 2012	$	10,375
Issuance of instruments		—
Change in value		(5,806	)
Net settlements		—
Value at September 30, 2013	$	4,569
Issuance of instruments		—
Change in value		211,860
Net settlements		—
Value at September 30, 2014	$	216,429

The derivative liabilities are estimated using option pricing models that are based on the individual characteristics of the warrants or instruments on the valuation date, as well as assumptions for expected volatility, expected life and risk-free interest rate. Changes in the assumptions used could have a material impact on the resulting fair value. The primary input affecting the value of our derivatives liabilities is the Company’s stock price. Other inputs have a comparatively insignificant effect.

During the year ended September 30, 2012, contingent consideration was recorded as an other non-current liability upon the acquisitions of Roche Madison Inc. and Alvos Therapeutics, Inc., totaling $173,621. The fair value measurement of the contingent consideration obligations is determined using Level 3 inputs. The fair value of contingent consideration obligations is based on a discounted cash flow model using a probability-weighted income approach. The measurement is based upon unobservable inputs supported by little or no market activity based on our own assumptions and experience. Estimating timing to complete the development, and obtain approval of products is difficult, and there are inherent uncertainties in developing a product candidate, such as obtaining U.S. Food and Drug Administration (FDA) and other regulatory approvals. In determining the probability of regulatory approval and commercial success, we utilize data regarding similar milestone events from several sources, including industry studies and our own experience. These fair value measurements represent Level 3 measurements as they are based on significant inputs not observable in the market. Significant judgment is employed in determining the appropriateness of these assumptions as of the acquisition date and for each subsequent period. Accordingly, changes in assumptions could have a material impact on the amount of contingent consideration expense we record in any given period. Changes in the fair value of the contingent consideration obligations are recorded in our Consolidated Statement of Operations.

The following is a reconciliation of contingent consideration fair value during the years ended September 30, 2014 and 2013.

Value at September 30, 2012	$	173,621
Purchase price contingent consideration		—
Contingent consideration payments		—
Change in fair value of contingent consideration		1,421,652
Value at September 30, 2013	$	1,595,273
Purchase price contingent consideration		—
Contingent consideration payments		—
Change in fair value of contingent consideration		2,375,658
Value at September 30, 2014	$	3,970,931

The fair value of contingent consideration obligations is estimated through valuation models designed to estimate the probability of such contingent payments based on various assumptions and incorporating estimated success rates. Estimated payments are discounted using present value techniques to arrive at estimated fair value at the balance sheet date. Changes in the fair value of the contingent consideration obligations can result from changes to one or multiple inputs, including adjustments to the discount rates, changes in the amount or timing of expected expenditures associated with product development, changes in the amount or timing of cash flows from products upon commercialization, changes in the assumed achievement or timing of any development milestones, changes in the probability of certain clinical events and changes in the assumed probability associated with regulatory approval. Each of these assumptions can have a significant impact on the calculation of contingent consideration.

The carrying amounts of the Company’s other financial instruments, which include accounts receivable, accounts payable, and accrued expenses approximate their respective fair values due to the relatively short-term nature of these instruments. The carrying value of the Company’s debt obligations approximates fair value based on market interest rates.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Income Taxes

12 Months Ended

Sep. 30, 2014

Income Tax Disclosure [Abstract]

Income Taxes

NOTE 11. - INCOME TAXES

The Company utilizes the guidance issued by the FASB for accounting for income taxes which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns.

Under this method, deferred income taxes are recognized for the tax consequences in future years of differences between the tax bases of assets and liabilities and their financial reporting amounts at each year-end based on enacted tax laws and statutory tax rates applicable to the periods in which the differences are expected to affect taxable income. Valuation allowances are established, when necessary, to reduce deferred tax assets to the amount expected to be realized. The provision for income taxes represents the tax payable for the period and the change during the period in deferred tax assets and liabilities.

Components of the net deferred tax asset (liability) at September 30, 2014 and 2013 are as follows:

		2014		2013
Deferred tax assets:
Reserve for other receivables	$	233,014		$	1,026,010
Accrued compensation		1,313,354			159,015
Stock compensation		3,011,369			1,269,020
Capitalized research and development		13,536,745			3,985,025
Fair value adjustments		1,864,364			749,030
Net operating losses		42,268,526			52,133,035
Total deferred tax assets		62,227,372			59,321,135
Valuation allowance		(55,224,802	)		(52,214,090	)
Deferred tax liabilities:
State taxes		(6,277,587	)		(5,042,010	)
Equity investments		(7,675	)		—
Intangible assets		(475,829	)		(1,521,015	)
Fixed assets		(241,479	)		(544,020	)
Total deferred tax liability		(7,002,570	)		(7,107,045	)
Net deferred tax assets	$	—		$	—

The Company’s book losses and other timing differences result in a net deferred income tax benefit which is offset by a valuation allowance for a net deferred asset of zero. The Company has concluded, in accordance with the applicable accounting standards, that it is more likely than not that the Company may not realize the benefit of all of its deferred tax assets. Accordingly, management has provided a 100% valuation allowance against its deferred tax assets until such time as management believes that its projections of future profits as well as expected future tax rates make the realization of these deferred tax assets more-likely-than-not. Significant judgment is required in the evaluation of deferred tax benefits and differences in future results from our estimates could result in material differences in the realization of these assets. As of September 30, 2014 and 2013, federal deferred tax assets were estimated to be $62.2 million and $59.3 million, respectively. The Company has recorded a full valuation allowance related to all of its deferred tax assets. The Company has performed an assessment of positive and negative evidence regarding the realization of the net deferred tax asset in accordance with FASB ASC 740-10, “Accounting for Income Taxes.” This assessment included the evaluation of scheduled reversals of deferred tax liabilities, the availability of carry forwards and estimates of projected future taxable income.

As of September 30, 2013, the Company had available gross federal net operating loss (NOL) carry forwards of $64.1 million and gross state NOL carry forwards of $80.0 million which expire at various dates through 2033. Gross federal NOL carry forwards for 2014 are estimated at $24.2 million, and gross state NOL carry forwards for 2014 are estimated at $37.9 million

The provision for income taxes for the years ended September 30, 2014 and 2013 are as follows:

	2014		2013
Federal:
Current		—		—
Deferred		—		—
Total Federal		—		—
State:
Current	$	5,300		—
Deferred		—		—
Total State	$	5,300		—
Provision from income taxes	$	5,300		—

The Company’s effective income tax rate differs from the statutory federal income tax rate as follows for the years ended September 30, 2014 and 2013:

	2014		2013
At U.S. federal statutory rate	34.0	%		34.0	%
State taxes, net of federal effect	7.6			10.3
Stock compensation	(0.1	)		(1.1	)
Mark-to-market adjustments	(3.5	)		(5.8
Other permanent items	(0.1	)		(0.0	)
Valuation allowance	(5.2	)		(37.4	)
Write-off of net operating losses	(32.7	)		(0.0	)
Effective income tax rate	0.0	%		0.0	%

The Company has adopted guidance issued by the FASB that clarifies the accounting for uncertainty in income taxes recognized in an enterprise’s financial statements and prescribes a recognition threshold of more likely than not and a measurement process for financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. In making this assessment, a company must determine whether it is more likely than not that a tax position will be sustained upon examination, based solely on the technical merits of the position and must assume that the tax position will be examined by taxing authorities. The Company’s policy is to include interest and penalties related to unrecognized tax benefits in income tax expense. The Company has not recognized any unrecognized tax benefits and does not have any interest or penalties related to uncertain tax positions as of September 30, 2014 and 2013.

The Company files income tax returns with the Internal Revenue Service (“IRS”), the state of California and certain other taxing jurisdictions. The Company is no longer subject to income tax examinations by the IRS for tax years through fiscal 2010 and by state tax authorities for tax years through fiscal 2009.

Employee Benefit Plans	12 Months Ended
Employee Benefit Plans	Sep. 30, 2014
Compensation And Retirement Disclosure [Abstract]
Employee Benefit Plans	NOTE 12. EMPLOYEE BENEFIT PLANS In January 2005, the Company adopted a defined contribution 401(k) retirement savings plan covering substantially all of its employees. The Plan is administered under the “safe harbor” provision of ERISA. Under the terms of the plan, an eligible employee may elect to contribute a portion of their salary on a pre-tax basis, subject to federal statutory limitations. The plan allows for a discretionary match in an amount up to 100% of each participant’s first 3% of compensation contributed plus 50% of each participant’s next 2% of compensation contributed. For the years ended September 30, 2014, 2013 and 2012, we recorded expenses under these plans of approximately $264,193, $191,947 and $162,495, respectively. In addition to the employee benefit plans described above, the Company provides certain employee benefit plans, including those which provide health and life insurance benefits to employees.

Unaudited Quarterly Financial Data

12 Months Ended

Sep. 30, 2014

Quarterly Financial Information Disclosure [Abstract]

Unaudited Quarterly Financial Data

NOTE 13. UNAUDITED QUARTERLY FINANCIAL DATA

The following table presents selected unaudited quarterly financial data for each full quarterly period of the years ended September 30, 2014 and 2013:

	First		Second		Third		Fourth
Year ended September 30, 2014	Quarter		Quarter		Quarter		Quarter
Revenues	$	43,750	$	43,750	$	43,750	$	43,750
Operating Losses	$	(7,009,382)	$	(11,212,498)	$	(12,700,100)	$	(22,354,306)
Net Loss	$	(10,685,372)	$	(13,982,700)	$	(11,626,451)	$	(22,430,889)
Net Loss Attributable to Arrowhead	$	(10,628,312)	$	(13,942,521)	$	(11,626,919)	$	(22,432,438)
Loss per share (Basic and Diluted)	$	(0.28)	$	(0.31)	$	(0.22)	$	(0.42)

	First		Second		Third		Fourth
Year ended September 30, 2013	Quarter		Quarter		Quarter		Quarter
Revenues	$	159,016	$	43,750	$	43,750	$	43,750
Operating Losses	$	(4,810,021)	$	(5,390,288)	$	(6,389,865)	$	(7,999,102)
Net Loss	$	(4,780,727)	$	(6,940,019)	$	(6,177,628)	$	(13,805,059)
Net Loss Attributable to Arrowhead	$	(4,614,159)	$	(6,757,937)	$	(6,079,010)	$	(13,692,183)
Loss per share (Basic and Diluted)	$	(0.33)	$	(0.41)	$	(0.23)	$	(0.43)

Organization and Significant Accounting Policies (Policies)	12 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]
Nature of Business	Nature of Business Arrowhead Research develops novel drugs to treat intractable diseases by silencing the genes that cause them. Using the broadest portfolio of RNA chemistries and efficient modes of delivery, Arrowhead therapies trigger the RNA interference mechanism to induce rapid, deep and durable knockdown of target genes. Arrowhead’s most advanced drug candidate in clinical development is ARC-520, which is designed to treat chronic hepatitis B infection by inhibiting the production of all HBV gene products. The goal is to reverse the immune suppression that prevents the body from controlling the virus and clearing the disease. Arrowhead’s second clinical candidate is ARC-AAT, a treatment for a rare liver disease associated with a genetic disorder that causes alpha-1 antitrypsin deficiency.
Liquidity	Liquidity Historically, the Company’s primary source of financing has been through the sale of securities of Arrowhead Research Corp. Research and development activities have required significant capital investment since the Company’s inception and we expect our operations to continue to require cash investment in fiscal 2015 and beyond as the Company continues its research and development efforts, as well as clinical trials, and related drug manufacturing. At September 30, 2014, the Company had $132.5 million in cash to fund operations. In addition to its cash resources, the Company has invested excess cash in investment grade commercial bonds maturing in less than 2 years. These bonds provide a source of liquidity, although the Company plans to hold them until maturity. At September 30, 2014, the Company had invested $44.7 million in these bonds. During the year ended September 30, 2014, the Company’s cash position increased by $113.4 million which was the result of the receipt of cash from the issuance of equity of $172.6 million and cash from the exercise of warrants and options of $12.9 million, partially offset by cash outflows of $35.4 million related to continuing operating activities, net cash invested in fixed income investments of $34.8 million, and capital expenditures of $1.7 million.
Principles of Consolidation	Principles of Consolidation— The consolidated financial statements include the accounts of Arrowhead and its Subsidiaries. Arrowhead’s primary operating subsidiary is Arrowhead Madison, which is located in Madison, Wisconsin, where the Company’s research and development facilities are located. All significant intercompany accounts and transactions are eliminated in consolidation, and noncontrolling interests are accounted for in the Company’s financial statements.
Basis of Presentation and Use of Estimates	Basis of Presentation and Use of Estimates—The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could materially differ from those estimates. Additionally, certain reclassifications have been made to prior period financial statements to conform to the current period presentation.
Cash and Cash Equivalents	Cash and Cash Equivalents—The Company considers all liquid debt instruments purchased with a maturity of three months or less to be cash equivalents. The Company had no restricted cash at September 30, 2014 and 2013, respectively.
Concentration of Credit Risk	Concentration of Credit Risk—The Company maintains bank accounts for its operations at two financial institutions. These accounts are insured by the Federal Deposit Insurance Corporation (FDIC) for up to $250,000 per account. Management believes the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which these deposits are held.
Investments	Investments—the Company may invest excess cash balances in short-term and long-term marketable debt securities. Investments may consist of certificates of deposits, money market accounts, government-sponsored enterprise securities, corporate bonds and/or commercial paper. The Company accounts for its investment in marketable securities in accordance with FASB ASC 320, Investments – Debt and Equity Securities. This statement requires certain securities to be classified into three categories: Held-to-maturity—Debt securities that the entity has the positive intent and ability to hold to maturity are reported at amortized cost. Trading Securities—Debt and equity securities that are bought and held primarily for the purpose of selling in the near term are reported at fair value, with unrealized gains and losses included in earnings. Available-for-Sale—Debt and equity securities not classified as either securities held-to-maturity or trading securities are reported at fair value with unrealized gains or losses excluded from earnings and reported as a separate component of shareholders’ equity. The Company classifies its investments in marketable debt securities based on the facts and circumstances present at the time of purchase of the securities. At September 30, 2014, the Company classified all of its investments as held-to-maturity. Held-to-maturity investments are measured and recorded at amortized cost on the Company’s Consolidated Balance Sheet. Discounts and premiums to par value of the debt securities are amortized to interest income/expense over the term of the security. No gains or losses on investment securities are realized until they are sold or a decline in fair value is determined to be other-than-temporary.
Property and Equipment	Property and Equipment—Property and equipment are recorded at cost, which may equal fair market value in the case of property and equipment acquired in conjunction with a business acquisition. Depreciation of property and equipment is recorded using the straight-line method over the respective useful lives of the assets ranging from three to seven years. Leasehold improvements are amortized over the lesser of the expected useful life or the remaining lease term. Long-lived assets, including property and equipment, are reviewed for impairment whenever events or circumstances indicate that the carrying amount of these assets may not be recoverable.
Intangible Assets subject to amortization	Intangible Assets Subject to Amortization—At September 30, 2014, intangible assets subject to amortization include certain license agreements. Intangible assets subject to amortization are reviewed for impairment whenever events or circumstances indicate that the carrying amount of these assets may not be recoverable.
In-Process Research & Development (IPR&D)	In-Process Research & Development (IPR&D)—IPR&D assets represent capitalized on-going research projects that Arrowhead acquired through business combinations. Such assets are initially measured at their acquisition date fair values. The amounts capitalized are being accounted for as indefinite-lived intangible assets, subject to impairment testing until completion or abandonment of R&D efforts associated with the project. Upon successful completion of a project, Arrowhead will make a determination as to the then remaining useful life of the intangible asset and begin amortization. Based on ASC 350 – Intangibles, Goodwill and Other, Arrowhead tests its indefinite-lived assets for impairment at least annually, through a two-step process. The first step is a qualitative assessment to determine if it is more likely than not that the indefinite lived assets are impaired. Arrowhead considers relevant events and circumstances that could affect the inputs used to determine the fair value of the intangible assets. If the qualitative assessment indicates that it is more likely than not that the intangible assets is impaired, a second step is performed which is a quantitative test to determine the fair value of the intangible asset. If the carrying amount of the intangible assets exceeds its fair value, an impairment loss is recorded in the amount of that excess. If circumstances determine that it is appropriate, the Company may also elect to bypass step one, and proceed directly to the second step.
Contingent Consideration	Contingent Consideration - The consideration for our acquisitions often includes future payments that are contingent upon the occurrence of a particular event. For example, milestone payments might be based on the achievement of various regulatory approvals or future sales milestones, and royalty payments might be based on drug product sales levels. We record a contingent consideration obligation for such contingent payments at fair value on the acquisition date. We estimate the fair value of contingent consideration obligations through valuation models designed to estimate the probability of the occurrence of such contingent payments based on various assumptions and incorporating estimated success rates. Estimated payments are discounted using present value techniques to arrive at estimated fair value at the balance sheet date. We revalue these contingent consideration obligations each reporting period. Changes in the fair value of our contingent consideration obligations are recognized within our Consolidated Statement of Operations. Changes in the fair value of the contingent consideration obligations can result from changes to one or multiple inputs, including adjustments to the discount rates, changes in the amount or timing of expected expenditures associated with product development, changes in the amount or timing of cash flows from products upon commercialization, changes in the assumed achievement or timing of any development milestones, changes in the probability of certain clinical events and changes in the assumed probability associated with regulatory approval. These fair value measurements are based on significant inputs not observable in the market. Significant judgment is employed in determining the appropriateness of these assumptions as of the acquisition date and for each subsequent period. Accordingly, changes in assumptions could have a material impact on the amount of contingent consideration expense we record in any given period.
Noncontrolling Interests in Majority-Owned Subsidiaries	Noncontrolling Interests in Majority-Owned Subsidiaries—Operating losses applicable to majority-owned Ablaris, Calando (prior to its deconsolidation), and Unidym (prior to its disposal) have periodically exceeded the noncontrolling interests in the equity capital of either Subsidiary. Such excess losses applicable to the noncontrolling interests have been and are borne by the Company as there is no obligation of the noncontrolling interests to fund any losses in excess of their original investment. There is also no obligation or commitment on the part of the Company to fund operating losses of any Subsidiary whether wholly-owned or majority-owned. The Company allocates the noncontrolling interest’s share of net loss in excess of the noncontrolling interest’s initial investment in accordance with FASB ASC 810-10. When there is a change in the Company’s proportionate share of a Subsidiary resulting from additional equity transactions in a Subsidiary, the change is accounted for as an equity transaction in consolidation. To the extent that the increase in the calculated value of the Company’s interest in the equity of the Subsidiary exceeds the Company’s investment in the offering, that increase in value is referred to as the Company’s “increase in its proportionate share of the Subsidiary’s equity” and the amount is recorded as an increase in the Company’s Additional Paid-in Capital.
Revenue Recognition	Revenue Recognition—Revenue from license fees are recorded when persuasive evidence of an arrangement exists, title has passed or services have been rendered, a price is fixed and determinable, and collection is reasonably assured. We may generate revenue from product sales, technology licenses, collaborative research and development arrangements, and research grants. Revenue under technology licenses and collaborative agreements typically consists of nonrefundable and/or guaranteed technology license fees, collaborative research funding and various milestone and future product royalty or profit-sharing payments. Revenue associated with research and development funding payments under collaborative agreements is recognized ratably over the relevant periods specified in the agreement, generally the research and development period. Revenue from up-front license fees, milestones and product royalties are recognized as earned based on the completion of the milestones and product sales, as defined in the respective agreements. Payments received in advance of recognition as revenue are recorded as deferred revenue.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts—The Company accrues an allowance for doubtful accounts based on estimates of uncollectible revenues by analyzing historical collections, accounts receivable aging and other factors. Accounts receivable are written off when all collection attempts have failed.
Research and Development	Research and Development—Costs and expenses that can be clearly identified as research and development are charged to expense as incurred in accordance with FASB ASC 730-10. Included in research and development costs are operating costs, facilities, supplies, external services, clinical trial and manufacturing costs, and overhead directly related to the Company’s research and development operations, as well as costs to acquire technology licenses.
Earnings (Loss) per Share	Earnings (Loss) per Share—Basic earnings (loss) per share is computed using the weighted-average number of common shares outstanding during the period. Diluted earnings (loss) per share are computed using the weighted-average number of common shares and dilutive potential common shares outstanding during the period. Dilutive potential common shares primarily consist of stock options and restricted stock units issued to employees and warrants to purchase Common Stock of the Company.
Stock-Based Compensation	Stock-Based Compensation—The Company accounts for share-based compensation arrangements in accordance with FASB ASC 718, which requires the measurement and recognition of compensation expense for all share-based payment awards to be based on estimated fair values. We use the Black-Scholes option valuation model to estimate the fair value of our stock options at the date of grant. The Black-Scholes option valuation model requires the input of subjective assumptions to calculate the value of stock options. We use historical data among other information to estimate the expected price volatility and the expected forfeiture rate. The fair value of restricted stock units granted is based upon the quoted closing market price per share on the date of grant, adjusted for assumed forfeitures. Expense for stock options and restricted stock units is recognized over the requisite service period.
Derivative Assets and Liabilities	Derivative Assets and Liabilities - We account for warrants and other derivative financial instruments as either equity or assets/liabilities based upon the characteristics and provisions of each instrument. Warrants classified as equity are recorded as additional paid-in capital on our Consolidated Balance Sheet and no further adjustments to their valuation are made. Some of our warrants were determined to be ineligible for equity classification because of provisions that may result in an adjustment to their exercise price. Warrants classified as derivative liabilities and other derivative financial instruments that require separate accounting as assets or liabilities are recorded on our Consolidated Balance Sheet at their fair value on the date of issuance and are revalued on each subsequent balance sheet date until such instruments are exercised or expire, with any changes in the fair value between reporting periods recorded as other income or expense. We estimate the fair value of these assets/liabilities using option pricing models that are based on the individual characteristics of the warrants or instruments on the valuation date, as well as assumptions for expected volatility, expected life and risk-free interest rate.
Income Taxes	Income Taxes—The Company accounts for income taxes under the liability method, which requires the recognition of deferred income tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Under this method, deferred income taxes are recognized for the tax consequences in future years of differences between the tax bases of assets and liabilities and their financial reporting amounts at each period end based on enacted tax laws and statutory tax rates applicable to the periods in which the differences are expected to affect taxable income. Valuation allowances are established, when necessary, to reduce deferred income tax assets to the amount expected to be realized. The provision for income taxes, if any, represents the tax payable for the period and the change in deferred income tax assets and liabilities during the period.
Recently Issued Accounting Standards	Recently Issued Accounting Standards In August 2014, the FASB issued ASU 2014-15, Presentation of Financial Statements – Going Concern (Topic 915): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern, which states that in connection with preparing financial statements for each annual and interim reporting period, an entity’s management should evaluate whether there are conditions or events, considered in the aggregate, that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date that the financial statements are issued (or within one year after the date that the financial statements are available to be issued when applicable). The adoption of this update did not have a material effect on our financial statements. In June 2014, the FASB issued ASU 2014-10, Development Stage Entities (Topic 915): Elimination of Certain Financial Reporting Requirements, Including an Amendment to Variable Interest Entities Guidance, which eliminates the distinction and separate requirements for development stage entities and other reporting entities under U.S. GAAP. Specifically the amendment eliminates the requirement for development stage entities to 1) present inception-to-date information in the statements of income, cash flow and shareholders’ equity, 2) label the financial statements as those of a development stage entity, 3) disclose a description of the development stage activities in which the entity is engaged and 4) disclose the first year in which the entity is no longer a development stage entity that in prior years it had been in the development stage. ASU 2014-10 is effective for fiscal years beginning after December 15, 2014 with early adoption permitted. The Company has adopted ASU 2014-10 effectively beginning with the filing of our Form 10-Q for period ended June 30, 2014. In May 2014, the FASB issued ASU No. 2014-09 Revenue from Contracts with Customers (Topic 606), which will supersede nearly all existing revenue recognition guidance under GAAP. ASU No. 2014-09 provides that an entity recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This update also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments, and assets recognized from costs incurred to obtain or fulfill a contract. ASU No. 2014-09 allows for either full retrospective or modified retrospective adoption and will become effective for the Company in the first quarter of 2018. The Company is evaluating the potential effects of the adoption of this update on its financial statements. In July 2013, the FASB issued ASU 2013-11, Income Taxes (Topic 740): Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists, which eliminates diversity in practice for the presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss or a tax credit carryforward is available to reduce the taxable income or tax payable that would result from disallowance of a tax position. ASU 2013-11 affects only the presentation of such amounts in an entity’s balance sheet and is effective for fiscal years beginning after December 15, 2013 and interim periods within those years. Early adoption is permitted. The adoption of this update did not have a material effect on our financial statements. In July 2012, the FASB issued ASU 2012-02, Testing Indefinite-Lived Intangible Assets for Impairment, which amended the guidance in ASU 2011-08 to simplify the testing of indefinite-lived intangible assets other than goodwill for impairment. ASU 2012-02 becomes effective for annual and interim impairment tests performed for fiscal years beginning on or after September 15, 2012 and earlier adoption is permitted. We adopted this standard in the third quarter of fiscal year 2012. The adoption of this update did not have a material effect on our financial statements.

Property and Equipment (Tables)

12 Months Ended

Sep. 30, 2014

Property Plant And Equipment [Abstract]

Summary of Property and Equipment

The following table summarizes our major classes of property and equipment:


	September 30, 2014			September 30, 2013
Computers, office equipment and furniture	$	334,162		$	323,376
Research equipment		4,614,176			3,452,013
Software		69,623			69,623
Leasehold improvements		3,045,022			2,749,409
Total gross fixed assets		8,062,983			6,594,421
Less: Accumulated depreciation and amortization		(4,190,230	)		(3,081,186	)
Property and equipment, net	$	3,872,753		$	3,513,235

Investments (Tables)

12 Months Ended

Sep. 30, 2014

Equity [Abstract]

Summary of Short and Long-term Investments

The following tables summarize the Company’s short and long-term investments as of September 30, 2014 and 2013, respectively:

	As of September 30, 2014
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Commercial notes (due within one year)	$	21,653,032	$	—	$	(189,830	)	$	21,463,202
Commercial notes (due after one year through two years)	$	23,088,346		—	$	(217,693	)	$	22,870,653
Total	$	44,741,378	$	—	$	(407,523	)	$	44,333,855

	As of September 30, 2013
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Commercial notes (due within one year)	$	9,030,261	$	7,500	$	(39,281	)	$	8,998,480
Commercial notes (due after one year through two years)	$	1,702,153		—	$	(2,362	)	$	1,699,791
Total	$	10,732,414	$	7,500	$	(41,643	)	$	10,698,271

- Definition

Tabular disclosure of all investments in certain debt and equity securities for which the entity has the positive intent and ability to hold until maturity.

+ References + Details

Intangible Assets (Tables)

12 Months Ended

Sep. 30, 2014

Goodwill And Intangible Assets Disclosure [Abstract]

Schedule of Intangible Asset

The below table provides details on our intangible asset balances:

	Intangible assets not subject to amortization		Intangible assets subject to amortization		Total Intangible assets
Balance at September 30, 2012	$	3,117,322	$	1,667,247	$	4,784,569
Impairment		-		(1,308,047)		(1,308,047	)
Amortization		-		(236,009)		(236,009	)
Balance at September 30, 2013	$	3,117,322	$	123,191	$	3,240,513
Impairment		(2,172,387)		-		(2,172,387	)
Amortization		-		(54,653)		(54,653	)
Balance at September 30, 2014	$	944,935	$	68,538	$	1,013,473

Stockholders' Equity (Tables)

12 Months Ended

Sep. 30, 2014

Equity [Abstract]

Summary of Information About Warrants

The following table summarizes information about warrants outstanding at September 30, 2014:

Exercise prices		Number of Warrants		Remaining Life in Years
$	70.60		94,897		2.6
$	5.00		413,825		0.9
$	5.09		269,912		0.2
$	1.38		24,324		1.2
$	4.16		1,000		2.2
$	3.25		334,347		1.9
$	2.12		75,000		3.2
$	1.83		277,284		3.2
Total warrants outstanding			1,490,589

- Definition

Tabular disclosure of warrants or rights issued. Warrants and rights outstanding are derivative securities that give the holder the right to purchase securities (usually equity) from the issuer at a specific price within a certain time frame. Warrants are often included in a new debt issue to entice investors by a higher return potential. The main difference between warrants and call options is that warrants are issued and guaranteed by the company, whereas options are exchange instruments and are not issued by the company. Also, the lifetime of a warrant is often measured in years, while the lifetime of a typical option is measured in months. Disclose the title of issue of securities called for by warrants and rights outstanding, the aggregate amount of securities called for by warrants and rights outstanding, the date from which the warrants or rights are exercisable, and the price at which the warrant or right is exercisable.

+ References + Details

Commitments and Contingencies (Tables)

12 Months Ended

Sep. 30, 2014

Leases [Abstract]

Future Minimum Lease Payments Under Capitalized Leases

As of September 30, 2014, future minimum lease payments due in fiscal years under capitalized leases are as follows:

2015	$	228,420
2016		228,420
2017		228,420
2018		228,420
2019		95,175
2020 and thereafter		-
Less interest		(36,524)
Principal		972,331
Less current portion		(213,991	)
Noncurrent portion	$	758,340

Future Minimum Lease Payments Under Operating Leases

As of September 30, 2014, future minimum lease payments due in fiscal years under operating leases are as follows:

2015	$	580,306
2016		596,877
2017		613,664
2018		637,897
2019		459,633
2020 and thereafter		-
Total	$	2,888,377

Stock-Based Compensation (Tables)

12 Months Ended

Sep. 30, 2014

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summarize Information about Stock Options

	Number of Options Outstanding			Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Term		Aggregate Intrinsic Value
Balance At September 30, 2012		1,910,794			6.10
Granted		1,509,166			2.03
Cancelled		-			-
Exercised		(675	)		3.93
Balance At September 30, 2013		3,419,285			4.68
Granted		1,039,000			14.05
Cancelled		(152,582)			6.05
Exercised		(454,863)			6.00
Balance At September 30, 2014		3,850,840			6.99		8.1 years		$31,141,826
Exercisable At September 30, 2014		1,684,919			5.94		7.2 years		$15,518,772

Assumptions Used to Value Stock Options

The assumptions used to value stock options are as follows:

	Year ended September 30,
	2014	2013	2012
Dividend yield	—	—	—
Risk-free interest rate	1.8% to 2.4%	0.7% to 2.3%	0.9% to 1.7%
Volatility	69%	69%	90% - 100%
Expected life (in years)	6.25 to 9.47	5.5 to 6.25	5.5 to 6.25
Weighted average grant date fair value per share of options granted	$8.92	$1.88	$3.32

Summary of Share Activity Related to Restricted Stock Units

The following table summarizes the activity of the Company’s Restricted Stock Units:

	Number of RSUs		Weighted- Average Grant Date Fair Value
Unvested at September 30, 2012		—	$	—
Granted		—		—
Vested		—		—
Forfeited		—		—
Unvested at September 30, 2013		—		—
Granted		510,000	$	14.58
Vested		—		—
Forfeited		—		—
Unvested at September 30, 2014		510,000	$	14.58

Fair Value Measurements (Tables)

12 Months Ended

Sep. 30, 2014

Fair Value Measurements for Assets and Liabilities Measured at Fair Value on Recurring Basis

The following table summarizes fair value measurements at September 30, 2014 and September 30, 2013 for assets and liabilities measured at fair value on a recurring basis:

September 30, 2014:

	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	132,510,610	$	—	$	—	$	132,510,610
Derivative liabilities	$	—	$	—	$	4,173,943	$	4,173,943
Contingent consideration obligations related to acquisitions	$	—	$	—	$	3,970,931	$	3,970,931

September 30, 2013:

	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	19,114,444	$	—	$	—	$	19,114,444
Derivative liabilities	$	—	$	—	$	4,096,363	$	4,096,363
Contingent consideration obligations related to acquisitions	$	—	$	—	$	1,595,273	$	1,595,273

Change in Fair Value of Contingent Consideration Obligations

The following is a reconciliation of contingent consideration fair value during the years ended September 30, 2014 and 2013.

Value at September 30, 2012	$	173,621
Purchase price contingent consideration		—
Contingent consideration payments		—
Change in fair value of contingent consideration		1,421,652
Value at September 30, 2013	$	1,595,273
Purchase price contingent consideration		—
Contingent consideration payments		—
Change in fair value of contingent consideration		2,375,658
Value at September 30, 2014	$	3,970,931

Exchange rights

Assumptions Used in Valuing Derivative Liabilities

The assumptions used in valuing the derivative liability as of September 30, 2014 and 2013 were as follows:

	September 30, 2014	September 30, 2013
Risk free interest rate	1.07%	1.39%
Expected life	3.3 Years	4.3 Years
Dividend yield	None	None
Volatility	100%	100%

Reconciliation of Derivative Liability

The following is a reconciliation of the derivative liability related to these exchange rights for the years ended September 30, 2014 and 2013:

Value at September 30, 2012	$	10,375
Issuance of instruments		—
Change in value		(5,806	)
Net settlements		—
Value at September 30, 2013	$	4,569
Issuance of instruments		—
Change in value		211,860
Net settlements		—
Value at September 30, 2014	$	216,429

Warrant

Assumptions Used in Valuing Derivative Liabilities

The assumptions used in valuing the derivative liability as of September 30, 2014 and 2013 were as follows:

2010 Warrants	September 30, 2014	September 30, 2013
Risk free interest rate	0.13%	0.33%
Expected life	1.2 Years	2.2 Years
Dividend yield	None	None
Volatility	69%	69%

2012 Warrants	September 30, 2014	September 30, 2013
Risk free interest rate	1.07%	1.39%
Expected life	3.2 Years	4.2 Years
Dividend yield	None	None
Volatility	69%	69%

2013 Warrants	September 30, 2014	September 30, 2013
Risk free interest rate	1.07%	1.39%
Expected life	3.3 Years	4.3 Years
Dividend yield	None	None
Volatility	69%	69%

Reconciliation of Derivative Liability

The following is a reconciliation of the derivative liability related to these warrants for the years ended September 30, 2014 and 2013:

Value at September 30, 2012	$	626,195
Issuance of instruments		2,153,819
Change in value		5,066,591
Net settlements		(3,754,808	)
Value at September 30, 2013	$	4,091,797
Issuance of instruments		—
Change in value		5,821,796
Net settlements		(5,956,079)
Value at September 30, 2014	$	3,957,514

Income Taxes (Tables)

12 Months Ended

Sep. 30, 2014

Income Tax Disclosure [Abstract]

Components of the Net Deferred Tax (Liability)

Components of the net deferred tax asset (liability) at September 30, 2014 and 2013 are as follows:

		2014		2013
Deferred tax assets:
Reserve for other receivables	$	233,014		$	1,026,010
Accrued compensation		1,313,354			159,015
Stock compensation		3,011,369			1,269,020
Capitalized research and development		13,536,745			3,985,025
Fair value adjustments		1,864,364			749,030
Net operating losses		42,268,526			52,133,035
Total deferred tax assets		62,227,372			59,321,135
Valuation allowance		(55,224,802	)		(52,214,090	)
Deferred tax liabilities:
State taxes		(6,277,587	)		(5,042,010	)
Equity investments		(7,675	)		—
Intangible assets		(475,829	)		(1,521,015	)
Fixed assets		(241,479	)		(544,020	)
Total deferred tax liability		(7,002,570	)		(7,107,045	)
Net deferred tax assets	$	—		$	—

Provision for Income Taxes

The provision for income taxes for the years ended September 30, 2014 and 2013 are as follows:

	2014		2013
Federal:
Current		—		—
Deferred		—		—
Total Federal		—		—
State:
Current	$	5,300		—
Deferred		—		—
Total State	$	5,300		—
Provision from income taxes	$	5,300		—

Summary of Effective Income Tax Rate Reconciliation

The Company’s effective income tax rate differs from the statutory federal income tax rate as follows for the years ended September 30, 2014 and 2013:

	2014		2013
At U.S. federal statutory rate	34.0	%		34.0	%
State taxes, net of federal effect	7.6			10.3
Stock compensation	(0.1	)		(1.1	)
Mark-to-market adjustments	(3.5	)		(5.8
Other permanent items	(0.1	)		(0.0	)
Valuation allowance	(5.2	)		(37.4	)
Write-off of net operating losses	(32.7	)		(0.0	)
Effective income tax rate	0.0	%		0.0	%

Unaudited Quarterly Financial Data (Tables)

12 Months Ended

Sep. 30, 2014

Quarterly Financial Information Disclosure [Abstract]

Schedule of Unaudited Quarterly Financial Data

The following table presents selected unaudited quarterly financial data for each full quarterly period of the years ended September 30, 2014 and 2013:

	First		Second		Third		Fourth
Year ended September 30, 2014	Quarter		Quarter		Quarter		Quarter
Revenues	$	43,750	$	43,750	$	43,750	$	43,750
Operating Losses	$	(7,009,382)	$	(11,212,498)	$	(12,700,100)	$	(22,354,306)
Net Loss	$	(10,685,372)	$	(13,982,700)	$	(11,626,451)	$	(22,430,889)
Net Loss Attributable to Arrowhead	$	(10,628,312)	$	(13,942,521)	$	(11,626,919)	$	(22,432,438)
Loss per share (Basic and Diluted)	$	(0.28)	$	(0.31)	$	(0.22)	$	(0.42)

	First		Second		Third		Fourth
Year ended September 30, 2013	Quarter		Quarter		Quarter		Quarter
Revenues	$	159,016	$	43,750	$	43,750	$	43,750
Operating Losses	$	(4,810,021)	$	(5,390,288)	$	(6,389,865)	$	(7,999,102)
Net Loss	$	(4,780,727)	$	(6,940,019)	$	(6,177,628)	$	(13,805,059)
Net Loss Attributable to Arrowhead	$	(4,614,159)	$	(6,757,937)	$	(6,079,010)	$	(13,692,183)
Loss per share (Basic and Diluted)	$	(0.33)	$	(0.41)	$	(0.23)	$	(0.43)

Organization and Significant Accounting Policies - Additional Information (Detail) - USD ($)	1 Months Ended	12 Months Ended
	May 31, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Schedule Of Investments [Line Items]
Cash to fund operations		$ 132,510,610	$ 19,114,444	$ 3,377,288	$ 7,507,389
Investments		44,741,378	10,732,414
Net increase (decrease) in cash		113,396,166	15,737,156	(4,130,101)
Cash from issuance of equity	$ 36,000,000	172,641,671	42,448,826	10,883,992
Proceeds from the exercise of warrants and stock options		12,878,044	2,057,178	74,239
Cash outflow related to continuing operating activities		(35,416,373)	(19,032,826)	(15,340,090)
Net cash invested in fixed income investments		34,800,000
Capital expenditures		1,717,362	296,880	$ 479,710
Restricted Cash		0	$ 0
Amount insured in FDIC per account		$ 250,000
Minimum
Schedule Of Investments [Line Items]
Property, Plant and Equipment, Useful Life		3 years
Maximum
Schedule Of Investments [Line Items]
Property, Plant and Equipment, Useful Life		7 years
Commercial bonds
Schedule Of Investments [Line Items]
Maturity description		less than 2 years
Investments		$ 44,700,000

Property and Equipment - Summary of Property and Equipment (Detail) - USD ($)	Sep. 30, 2014	Sep. 30, 2013
Property Plant And Equipment [Abstract]
Computers, office equipment and furniture	$ 334,162	$ 323,376
Research equipment	4,614,176	3,452,013
Software	69,623	69,623
Leasehold improvements	3,045,022	2,749,409
Total gross fixed assets	8,062,983	6,594,421
Less: Accumulated depreciation and amortization	(4,190,230)	(3,081,186)
Property and equipment, net	$ 3,872,753	$ 3,513,235

Investments - Summary of Short and Long-term Investments (Detail) - USD ($)	Sep. 30, 2014	Sep. 30, 2013
Schedule Of Investments [Line Items]
Gross Unrealized Gains		$ 7,500
Gross Unrealized Losses	(407,523)	(41,643)
Fair Value	44,333,855	10,698,271
Commercial notes (due within one year), amortized cost	21,653,032	9,030,261
Commercial notes (due after one year through two years), amortized cost	23,088,346	1,702,153
Total	44,741,378	10,732,414
Commercial Notes Due Within One Year
Schedule Of Investments [Line Items]
Gross Unrealized Gains		7,500
Gross Unrealized Losses	(189,830)	(39,281)
Fair Value	21,463,202	8,998,480
Commercial Notes Due After One Year Through Two Years
Schedule Of Investments [Line Items]
Gross Unrealized Gains
Gross Unrealized Losses	(217,693)	(2,362)
Fair Value	$ 22,870,653	$ 1,699,791

Acquisitions - Additional Information (Detail) - USD ($)	1 Months Ended	12 Months Ended
	Oct. 21, 2011	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Business Acquisition [Line Items]
Obligation to pay royalties		later of (i) the expiration of the last to expire patent right related to such product candidate that was transferred in the Transaction and (ii) ten years after the first commercial sale of such product candidate.
Net present value of contingent consideration	$ 84,935
Contingent consideration		$ 3,970,931	$ 1,595,273	$ 173,621
Contingent consideration - Fair Value Adjustments		$ 2,375,658	$ 1,421,652
Roche Madison Inc
Business Acquisition [Line Items]
Issue of promissory note to Roche	$ 50,000
Issue of Common Stock	1,288,158
Applicable out-license term		90 days
Percentage of royalty liability		3.00%
Cash payments to Roche, minimum		$ 2,500,000
Cash payments to Roche, maximum		$ 6,000,000

Intangible Assets - Additional Information (Detail) - USD ($)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012	Jun. 30, 2013
Expected Amortization Expense [Line Items]
Intangible assets not subject to amortization, Impairment	$ 2,172,387
Capitalized intangible asset net book value	$ 68,538	$ 123,191	$ 1,667,247
Amortization period of intangible assets	12 years
Amortization of license agreements in 2015	$ 55,000
Amortization of license agreements in 2016	13,000
Amortization of license agreements, thereafter	0
Amortization expense	54,653	236,009	$ 293,964
Finite-lived intangible assets, accumulated amortization	$ 161,500
Patents
Expected Amortization Expense [Line Items]
Intangible assets not subject to amortization, Impairment		$ 1,300,000
Capitalized intangible asset net book value				$ 1,300,000
Patents \| Minimum
Expected Amortization Expense [Line Items]
Amortization period of intangible assets	3 years
Patents \| Maximum
Expected Amortization Expense [Line Items]
Amortization period of intangible assets	20 years
Licensing Agreements
Expected Amortization Expense [Line Items]
Amortization period of intangible assets	4 years

Intangible Assets - Schedule of Intangible Asset (Detail) - USD ($)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible assets not subject to amortization, beginning balance	$ 3,117,322	$ 3,117,322
Intangible assets not subject to amortization, Impairment	(2,172,387)
Intangible assets not subject to amortization, ending balance	944,935	3,117,322	$ 3,117,322
Intangible assets subject to amortization, beginning balance	123,191	1,667,247
Intangible assets subject to amortization, Impairment		(1,308,047)
Intangible assets subject to amortization, Amortization	(54,653)	(236,009)	(293,964)
Intangible assets subject to amortization, ending balance	68,538	123,191	1,667,247
Total Intangible assets, beginning balance	3,240,513	4,784,569
Total Intangible assets, Impairment	(2,172,387)	(1,308,047)
Total Intangible assets, Amortization	(54,653)	(236,009)	(293,964)
Total Intangible assets, ending balance	$ 1,013,473	$ 3,240,513	$ 4,784,569

Investment in Subsidiaries - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2011
Schedule Of Investments [Line Items]
Ownership percentage in subsidiary	100.00%
Ablaris Therapeutics
Schedule Of Investments [Line Items]
Ownership percentage in subsidiary	64.00%
Issuance of preferred stock in subsidiary		$ 2,900
Investment in preferred stock		1,300
Investment in preferred stock by outsider		$ 1,600
Percentage of investment ownership	64.00%
Calando Pharmaceuticals Inc
Schedule Of Investments [Line Items]
Ownership percentage in subsidiary	79.00%
Percentage of investment ownership	76.00%
Deconsolidation, Revaluation of Retained Investment, Gain (Loss), Amount	$ 87
Amount owed by subsidiary	$ 4,500
Stated percentage of notes and advances	8.00%

Stockholders' Equity - Additional Information (Detail)					1 Months Ended						12 Months Ended
Stockholders' Equity - Additional Information (Detail)	Feb. 24, 2014 USD ($) $ / shares shares	Oct. 11, 2013 USD ($) $ / shares shares	Aug. 10, 2012 USD ($) $ / shares shares	Oct. 21, 2011 USD ($) $ / shares shares	May 31, 2013 USD ($) $ / shares shares	Jan. 31, 2013 USD ($) $ / shares shares	Dec. 31, 2012 USD ($) $ / shares shares	Feb. 29, 2012 shares	Nov. 17, 2011 shares	Oct. 31, 2011 USD ($) shares	Sep. 30, 2014 USD ($) $ / shares shares	Sep. 30, 2013 USD ($) $ / shares shares	Sep. 30, 2012 USD ($) shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Capital stock authorized for issuance											150,000,000
Common stock, shares authorized											145,000,000	145,000,000
Common stock, par value \| $ / shares				$ 0.001							$ 0.001	$ 0.001
Preferred stock, shares authorized											5,000,000	5,000,000
Preferred stock, par value \| $ / shares											$ 0.001	$ 0.001
Common stock, shares outstanding											54,656,936	32,489,444
Preferred stock, shares outstanding											18,300	9,900
Threshold percentage of common stock ownership upon preferred stock conversion											9.99%
Issuance and sale of Common Stock	6,325,000	3,071,672	2,260,869			1,667,051	1,825,079
Sale of stock, price per share \| $ / shares	$ 18.95	$ 5.86	$ 2.76			$ 2.12	$ 2.26
Unit sold, description			Each unit consisted of one share of Common Stock and a warrant to purchase			Each unit consisted of one share of Common Stock and a warrant to purchase	Each unit consisted of one share of Common Stock and a warrant to purchase
Warrant to purchase common stock			0.75			0.5
Common stock exercise price \| $ / shares			$ 3.25
Proceeds from issuance of common stock and warrants, net \| $	$ 112,600,000	$ 60,000,000	$ 6,200,000			$ 3,500,000	$ 4,100,000
Exercise price of warrant \| $ / shares											$ 1.83
Ratio of Common Stock to purchase for 1 Warrant							0.5
Conversion price \| $ / shares		$ 5.86			$ 1.83
Cash from issuance of equity \| $					$ 36,000,000						$ 172,641,671	$ 42,448,826	$ 10,883,992
Warrants issued					0
Aggregate price on issuance or Sale of equity \| $		$ 64,000,000
Fractional shares of common stock issued in connection of reverse stock split									0
Roche
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Reverse stock split ratio									0.1
Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance and sale of Common Stock					14,300,000
Sale of stock, price per share \| $ / shares				$ 3.70	$ 1.83
Preferred stock converted to common stock, Shares											9,272,459		275,782
Aggregate purchase price on issuance of common stock to be received \| $				$ 2,497,500
Fractional shares of common stock issued in connection of reverse stock split													131
Subscription Agreement
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance and sale of Common Stock				675,000
Series B Preferred Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares outstanding											1,256,831
Preferred stock, shares outstanding											2,300
Series C Preferred Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares outstanding											2,730,375
Preferred stock, shares outstanding											16,000
Issuance and sale of Common Stock		46,000
Sale of stock, price per share \| $ / shares		$ 1,000
Series A Preferred Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Preferred stock, par value \| $ / shares				$ 0.001
Sale of stock, price per share \| $ / shares				$ 1,000
Issuance of preferred stock in subsidiary \| $										$ 1,015,000
Number of shares converted in common stock								1,015		1,015
Preferred stock converted to common stock, Shares								275,782
Series A Preferred Stock \| Subscription Agreement
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance and sale of Common Stock										1,015
Series B convertible preferred stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance and sale of Common Stock					9,900
Sale of stock, price per share \| $ / shares					$ 1,000
2000 Stock Option Plan, 2004 Equity Incentive Plan, 2013 Equity Incentive Plan, and Inducement Grants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share reserve for issuance											7,165,174

Stockholders' Equity - Summary of Information About Warrants (Detail)	12 Months Ended
	Sep. 30, 2014 $ / shares shares
Class Of Warrant Or Right [Line Items]
Exercise prices \| $ / shares	$ 1.83
Number of Warrants \| shares	1,490,589
Warrant 1
Class Of Warrant Or Right [Line Items]
Exercise prices \| $ / shares	$ 70.60
Number of Warrants \| shares	94,897
Remaining Life in Years	2 years 7 months 6 days
Warrant 2
Class Of Warrant Or Right [Line Items]
Exercise prices \| $ / shares	$ 5.00
Number of Warrants \| shares	413,825
Remaining Life in Years	10 months 24 days
Warrant 3
Class Of Warrant Or Right [Line Items]
Exercise prices \| $ / shares	$ 5.09
Number of Warrants \| shares	269,912
Remaining Life in Years	2 months 12 days
Warrant 4
Class Of Warrant Or Right [Line Items]
Exercise prices \| $ / shares	$ 1.38
Number of Warrants \| shares	24,324
Remaining Life in Years	1 year 2 months 12 days
Warrant 5
Class Of Warrant Or Right [Line Items]
Exercise prices \| $ / shares	$ 4.16
Number of Warrants \| shares	1,000
Remaining Life in Years	2 years 2 months 12 days
Warrant 6
Class Of Warrant Or Right [Line Items]
Exercise prices \| $ / shares	$ 3.25
Number of Warrants \| shares	334,347
Remaining Life in Years	1 year 10 months 24 days
Warrant 7
Class Of Warrant Or Right [Line Items]
Exercise prices \| $ / shares	$ 2.12
Number of Warrants \| shares	75,000
Remaining Life in Years	3 years 2 months 12 days
Warrant 8
Class Of Warrant Or Right [Line Items]
Exercise prices \| $ / shares	$ 1.83
Number of Warrants \| shares	277,284
Remaining Life in Years	3 years 2 months 12 days

Commitments and Contingencies - Additional Information (Detail) - USD ($)	1 Months Ended	12 Months Ended
	Aug. 31, 2012	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Other Commitments [Line Items]
Facility and equipment rent expense		$ 554,000	$ 534,000	$ 480,000
Provision for recorded liabilities		0
Future commitments		21,400,000
Commitments expected to be incurred in fiscal 2015		19,500,000
Commitments expected to be incurred beyond fiscal 2015		1,900,000
Corporate Headquarters In Pasadena
Other Commitments [Line Items]
Rental expense	$ 23,000
Operating lease expiration date	Sep. 30, 2019
Percentage of increase in annual rental cost	3.00%
Research Facility in Madison
Other Commitments [Line Items]
Rental expense		$ 25,000
Operating lease expiration date		Feb. 28, 2019
Rental expenses include common area maintenance and real estate taxes		$ 16,000
Utilities costs per month		15,000
Increase in total monthly expenditures		75,000
Research Facility in Madison \| Assets Held under Capital Leases
Other Commitments [Line Items]
Monthly payments under capital lease		$ 19,000

Commitments and Contingencies - Future Minimum Lease Payments Under Capitalized Leases (Detail) - USD ($)	Sep. 30, 2014	Sep. 30, 2013
Leases [Abstract]
2015	$ 228,420
2016	228,420
2017	228,420
2018	228,420
2019	95,175
2020 and thereafter
Less interest	(36,524)
Principal	972,331
Less current portion	(213,991)	$ (221,345)
Noncurrent portion	$ 758,340	$ 1,061,113

Commitments and Contingencies - Future Minimum Lease Payments Under Operating Leases (Detail)	Sep. 30, 2014 USD ($)
Leases [Abstract]
2015	$ 580,306
2016	596,877
2017	613,664
2018	637,897
2019	459,633
2020 and thereafter
Total	$ 2,888,377

Stock-Based Compensation - Additional Information (Detail) - USD ($)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserve for issuance	467,322
Options and restricted stock units outstanding	3,850,840	3,419,285	1,910,794
Options and restricted stock units granted	1,039,000	1,509,166
Dividend yield	0.00%	0.00%	0.00%
Arrowhead
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized pre-tax compensation expense	$ 10,517,380
Weighted average period to recognize pre-tax compensation expense	3 years 1 month 6 days
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Units granted outside of Equity Incentive plans	40,000
Stock-based compensation expense	$ 2,551,397	$ 0	$ 0
Number of restricted stock units issued under 2013 incentive plan	510,000	0	0
Number of restricted stock units outstanding, granted	510,000
Restricted Stock Units (RSUs) \| Arrowhead
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized pre-tax compensation expense	$ 4,913,516
Weighted average period to recognize pre-tax compensation expense	1 year 6 months
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Units granted outside of Equity Incentive plans	185,000
Stock-based compensation expense	$ 3,144,776	$ 1,536,271	$ 1,241,404
Fair value of the options granted	9,267,048	2,843,575	4,091,117
Intrinsic value of the options exercised	$ 4,360,850	$ 554	$ 0
Dividend yield	0.00%
2000 Stock Option Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserve for issuance	38,000
2000 Stock Option Plan \| Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options and restricted stock units outstanding	38,000
2004 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserve for issuance	2,659,852
Options and restricted stock units granted	0
2004 Equity Incentive Plan \| Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options and restricted stock units outstanding	2,563,518
2013 Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserve for issuance	4,000,000
Options and restricted stock units granted	1,324,000
2013 Incentive Plan \| Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options and restricted stock units outstanding	1,292,000
2013 Incentive Plan \| Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of restricted stock units outstanding, granted	470,000

Stock-Based Compensation - Summarize Information about Stock Options (Detail) - USD ($)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Options Outstanding, beginning balance	3,419,285	1,910,794
Number of Options Outstanding, Granted	1,039,000	1,509,166
Number of Options Outstanding, Cancelled	(152,582)
Number of Options Outstanding, Exercised	(454,863)	(675)
Number of Options Outstanding, ending balance	3,850,840	3,419,285
Number of Options Outstanding, Exercisable	1,684,919
Weighted Average Exercise Price Per Share, beginning balance	$ 4.68	$ 6.10
Weighted Average Exercise Price Per Share, Granted	14.05	2.03
Weighted Average Exercise Price Per Share, Cancelled	6.05
Weighted Average Exercise Price Per Share, Exercised	6.00	3.93
Weighted Average Exercise Price Per Share, ending balance	6.99	$ 4.68
Weighted Average Exercise Price Per Share, Exercisable	$ 5.94
Weighted Average Remaining Contractual Term	8 years 1 month 6 days
Weighted Average Remaining Contractual Term, Exercisable	7 years 2 months 12 days
Aggregate Intrinsic Value	$ 31,141,826
Aggregate Intrinsic Value, Exercisable	$ 15,518,772

Stock-Based Compensation - Assumptions Used to Value Stock Options (Detail) - $ / shares	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend yield	0.00%	0.00%	0.00%
Risk-free interest rate, minimum	1.80%	0.70%	0.90%
Risk-free interest rate, maximum	2.40%	2.30%	1.70%
Volatility, minimum			90.00%
Volatility, maximum			100.00%
Volatility	69.00%	69.00%
Weighted average grant date fair value per share of options granted	$ 8.92	$ 1.88	$ 3.32
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life (in years)	6 years 3 months	5 years 6 months	5 years 6 months
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life (in years)	9 years 5 months 19 days	6 years 3 months	6 years 3 months

Stock-Based Compensation - Summary of Restricted Stock Activity (Detail) - Restricted Stock Units (RSUs) - $ / shares	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares, Unvested, beginning of period	0	0
Number of restricted stock units outstanding, granted	510,000
Shares, Vested
Shares, Forfeited
Shares, Unvested, End of period	510,000	0
Weighted average grant date fair value, beginning balance
Weighted average grant date fair value, Granted	14.58
Weighted average grant date fair value, Vested
Weighted average grant date fair value, Forfeited
Weighted average grant date fair value, ending balance	$ 14.58

Fair Value Measurements - Fair Value Measurements for Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($)	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative liabilities	$ 4,173,943	$ 4,096,363
Contingent consideration	3,970,931	1,595,273	$ 173,621
Fair Value, Measurements, Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	132,510,610	19,114,444
Derivative liabilities	4,173,943	4,096,363
Contingent consideration	3,970,931	1,595,273
Fair Value, Measurements, Recurring \| Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	132,510,610	19,114,444
Fair Value, Measurements, Recurring \| Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative liabilities	4,173,943	4,096,363
Contingent consideration	$ 3,970,931	$ 1,595,273

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References + Details

Fair Value Measurements - Additional Information (Detail)	12 Months Ended
	Sep. 30, 2014 USD ($) shares	Sep. 30, 2013 USD ($)	Jan. 31, 2013 shares	Dec. 31, 2012 shares	Jun. 30, 2010 shares
Fair Value Measurements Disclosure [Line Items]
Short term investments \| $	$ 21,653,032	$ 9,030,261
Investments \| $	23,088,346	1,702,153
Total investments \| $	44,741,378	10,732,414
Fair value of investment \| $	44,333,855	$ 10,698,271
Non-cash gain (loss) from change in fair value of the derivative liability \| $	$ (5,821,796)
Warrants outstanding	1,490,589
Duration of exchange rights	7 years
Ablaris Therapeutics
Fair Value Measurements Disclosure [Line Items]
Non-cash gain (loss) from change in fair value of the derivative liability \| $	$ (211,860)
Exchange right convertible conversion ratio for first year	0.06
Exchange right convertible conversion ratio for second year	0.04
Exchange right convertible conversion ratio for third year	0.03
Exchange right convertible conversion ratio for fourth year	0.02
Exchange right convertible conversion ratio for fifth year and beyond	0.01
Number of exchange right sold	675,000
2010 Warrants
Fair Value Measurements Disclosure [Line Items]
Warrants issued to acquire Common Stock					329,649
Warrants outstanding	24,324
2012 Warrants
Fair Value Measurements Disclosure [Line Items]
Warrants issued to acquire Common Stock				912,543
Warrants outstanding	265,161
2013 Warrants
Fair Value Measurements Disclosure [Line Items]
Warrants issued to acquire Common Stock			833,530
Warrants outstanding	12,123

Fair Value Measurements - Assumptions Used in Valuing Derivative Liabilities (Detail)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
2010 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Risk free interest rate	0.13%	0.33%
Expected life	1 year 2 months 12 days	2 years 2 months 12 days
Dividend yield
Volatility	69.00%	69.00%
2012 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Risk free interest rate	1.07%	1.39%
Expected life	3 years 2 months 12 days	4 years 2 months 12 days
Dividend yield
Volatility	69.00%	69.00%
2013 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Risk free interest rate	1.07%	1.39%
Expected life	3 years 3 months 18 days	4 years 3 months 18 days
Dividend yield
Volatility	69.00%	69.00%
Exchange rights
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Risk free interest rate	1.07%	1.39%
Expected life	3 years 3 months 18 days	4 years 3 months 18 days
Dividend yield
Volatility	100.00%	100.00%

Fair Value Measurements - Reconciliation of Derivative Liability (Detail) - USD ($)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Change in value	$ (5,821,796)
Exchange rights
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Value, Beginning balance	4,569	$ 10,375
Issuance of instruments
Change in value	211,860	(5,806)
Net settlements
Value, Ending balance	216,429	4,569
Warrant
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Value, Beginning balance	4,091,797	626,195
Issuance of instruments		2,153,819
Change in value	5,821,796	5,066,591
Net settlements	(5,956,079)	(3,754,808)
Value, Ending balance	$ 3,957,514	$ 4,091,797

Fair Value Measurements - Change in Fair Value of Contingent Consideration Obligations (Detail) - USD ($)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Business Combinations [Abstract]
Value, Beginning balance	$ 1,595,273	$ 173,621
Purchase price contingent consideration	0	0
Contingent consideration payments	0	0
Change in fair value of contingent consideration	2,375,658	1,421,652
Value, Ending balance	$ 3,970,931	$ 1,595,273

Income Taxes - Components of the Net Deferred Tax (Liability) and Asset (Detail) - USD ($)	Sep. 30, 2014	Sep. 30, 2013
Deferred tax assets:
Reserve for other receivables	$ 233,014	$ 1,026,010
Accrued compensation	1,313,354	159,015
Stock compensation	3,011,369	1,269,020
Capitalized research and development	13,536,745	3,985,025
Fair value adjustments	1,864,364	749,030
Net operating losses	42,268,526	52,133,035
Total deferred tax assets	62,227,372	59,321,135
Valuation allowance	(55,224,802)	(52,214,090)
Deferred tax liabilities:
State taxes	(6,277,587)	(5,042,010)
Equity investments	(7,675)
Intangible assets	(475,829)	(1,521,015)
Fixed assets	(241,479)	(544,020)
Total deferred tax liability	(7,002,570)	(7,107,045)
Net deferred tax assets

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Income Tax Disclosure [Abstract]
Valuation allowance against deferred tax assets	100.00%
Deferred tax assets	$ 62,227,372	$ 59,321,135
Gross federal net operating loss carry forwards	24,200,000	64,100,000
Gross state net operating loss carry forwards	$ 37,900,000	$ 80,000,000

Income Taxes - Provision for Income Taxes (Detail) - USD ($)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Federal:
Current
Deferred
Total Federal
State:
Current	5,300
Deferred
Total State	5,300
Provision from income taxes	$ 5,300

Income Taxes - Summary of Effective Income Tax Rate Reconciliation (Detail)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Income Tax Disclosure [Abstract]
At U.S. federal statutory rate	34.00%	34.00%
State taxes, net of federal effect	7.60%	10.30%
Stock compensation	(0.10%)	(1.10%)
Mark-to-market adjustments	(3.50%)	(5.80%)
Other permanent items	(0.10%)	(0.00%)
Valuation allowance	(5.20%)	(37.40%)
Write-off of net operating losses	(32.70%)	(0.00%)
Effective income tax rate	0.00%	0.00%

Employee Benefit Plans - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Defined Benefit Plan Disclosure [Line Items]
Employee benefits costs	$ 264,193	$ 191,947	$ 162,495
Discretionary Contributions
Defined Benefit Plan Disclosure [Line Items]
Discretionary match percentage	100.00%
Employee Contributions upto 3%
Defined Benefit Plan Disclosure [Line Items]
Percentage of compensation	3.00%
50% Percentage of Matching Contribution
Defined Benefit Plan Disclosure [Line Items]
Discretionary match percentage	50.00%
Employee Contribution Next 2%
Defined Benefit Plan Disclosure [Line Items]
Percentage of compensation	2.00%

Unaudited Quarterly Financial Data - Summary of Unaudited Quarterly Financial Data (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 43,750	$ 43,750	$ 43,750	$ 43,750	$ 43,750	$ 43,750	$ 43,750	$ 159,016	$ 175,000	$ 290,266	$ 146,875
Operating Losses	(22,354,306)	(12,700,100)	(11,212,498)	(7,009,382)	(7,999,102)	(6,389,865)	(5,390,288)	(4,810,021)	(53,276,286)	(24,589,276)	(21,089,211)
Net loss	(22,430,889)	(11,626,451)	(13,982,700)	(10,685,372)	(13,805,059)	(6,177,628)	(6,940,019)	(4,780,727)	(58,725,412)	(31,703,433)	(22,110,723)
Net Loss Attributable to Arrowhead	$ (22,432,438)	$ (11,626,919)	$ (13,942,521)	$ (10,628,312)	$ (13,692,183)	$ (6,079,010)	$ (6,757,937)	$ (4,614,159)	$ (58,630,190)	$ (31,143,289)	$ (21,125,928)
Loss per share (Basic and Diluted)	$ (0.42)	$ (0.22)	$ (0.31)	$ (0.28)	$ (0.43)	$ (0.23)	$ (0.41)	$ (0.33)	$ (1.25)	$ (1.30)	$ (1.90)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details