Consolidated Statement of Stockholders' Equity (USD $)	Total	Issued For Cash At $0.01 Per Unit	Issued For Cash At $10.00 Per Unit	Issued For Marketable Securities At $10.00 Per Unit	Issued For Cash At $15.00 Per Unit	Arrowheads Increase In Proportionate Share Of Calando's Equity	Issued as a Gift for $10.90 Per Share	Issued As Stock Issuance Cost At $15.00 Per Unit	Exercised At $2.00 Per Share	Exercised At $10.00 Per Share	Exercised At $15.00 Per Share	Issued To Purchase Insert Therapeutics Share At $39.80 Per Share	Issued At $48.80 Per Share	Issued At $38.40 Per Share	Issued At $35.00 Per Share	Issued At $59.10 Per Share	Issued At $57.80 Per Share	Issued For Purchase Of Carbon Nanotechnologies Inc At $37.70 Per Share	Issued At $27.20 Per Share To Rice University	Issued At $28.30 Per Share To Purchase Shares Of Unidym Inc	Issued At $29.50 per Share To Purchase MASA Energy LLC	Issued At $21.90 Per Share To Unidym For The Acquisition Of Nanoconduction	Issued At $21.80 Per Share	Issued At $5.50 Per Share To Unidym Stockholder In Exchange For Unidym's Shares	Issued At $5.20 Per Share To TEL Ventures In Exchange For Unidym's Shares	Issued At $6.30 Per Share	Issued At $13.12 Per Share	Issued At $3.80 Per Share	Issued At $3.70 Per Share	Issued at $4.00 Per Share	Issued @ $6.23 per share	Issued @ $5.11 per share	Issued To Unidym Stockholders In Exchange For Unidym's Shares	Issued To Calando Stockholders In Exchange For Calando's Shares	Issued In Acquisition	Preferred Stock Issued At $1,000 Per Share	Common Stock	Common Stock Issued For Cash At $0.01 Per Unit	Common Stock Issued For Cash At $10.00 Per Unit	Common Stock Issued For Marketable Securities At $10.00 Per Unit	Common Stock Issued For Cash At $15.00 Per Unit	Common Stock Issued as a Gift for $10.90 Per Share	Common Stock Issued As Stock Issuance Cost At $15.00 Per Unit	Common Stock Exercised At $2.00 Per Share	Common Stock Exercised At $10.00 Per Share	Common Stock Exercised At $15.00 Per Share	Common Stock Issued To Purchase Insert Therapeutics Share At $39.80 Per Share	Common Stock Issued At $48.80 Per Share	Common Stock Issued At $38.40 Per Share	Common Stock Issued At $35.00 Per Share	Common Stock Issued At $59.10 Per Share	Common Stock Issued To Purchase Calando Pharmaceuticals Inc At $51.70 Per Share	Common Stock Issued At $57.80 Per Share	Common Stock Issued For Purchase Of Carbon Nanotechnologies Inc At $37.70 Per Share	Common Stock Issued At Approximately $18.00 Per Share Net	Common Stock Issued At $27.20 Per Share To Rice University	Common Stock Issued At $28.30 Per Share To Purchase Shares Of Unidym Inc	Common Stock Issued At $29.50 per Share To Purchase MASA Energy LLC	Common Stock Issued At $21.90 Per Share To Unidym For The Acquisition Of Nanoconduction	Common Stock Issued At $21.80 Per Share	Common Stock Issued At $5.50 Per Share To Unidym Stockholder In Exchange For Unidym's Shares	Common Stock Issued At $5.20 Per Share To TEL Ventures In Exchange For Unidym's Shares	Common Stock Issued At $3.00 Per Share	Common Stock Issued At $6.30 Per Share	Common Stock Issued At $13.12 Per Share	Common Stock Issued At $3.80 Per Share	Common Stock Issued At $3.70 Per Share	Common Stock Issued at $4.00 Per Share	Common Stock Issued @ $6.23 per share	Common Stock Issued @ $5.11 per share	Common Stock Issued To Unidym Stockholders In Exchange For Unidym's Shares	Common Stock Issued To Calando Stockholders In Exchange For Calando's Shares	Common Stock Issued In Acquisition	Common Stock Issued Under Committed Capital Agreement	Preferred Stock	Preferred Stock Preferred Stock Issued At $1,000 Per Share	Additional Paid-In Capital	Additional Paid-In Capital Issued For Cash At $10.00 Per Unit	Additional Paid-In Capital Issued For Marketable Securities At $10.00 Per Unit	Additional Paid-In Capital Issued For Cash At $15.00 Per Unit	Additional Paid-In Capital Stock Issuance Cost Charged To Additional Paid In Capital	Additional Paid-In Capital Arrowheads Increase In Proportionate Share Of Insert Therapeutics Equity	Additional Paid-In Capital Arrowheads Increase In Proportionate Share Of Calando's Equity	Additional Paid-In Capital Issued as a Gift for $10.90 Per Share	Additional Paid-In Capital Issued As Stock Issuance Cost At $15.00 Per Unit	Additional Paid-In Capital Exercised At $2.00 Per Share	Additional Paid-In Capital Exercised At $10.00 Per Share	Additional Paid-In Capital Exercised At $15.00 Per Share	Additional Paid-In Capital Issued To Purchase Insert Therapeutics Share At $39.80 Per Share	Additional Paid-In Capital Issued At $48.80 Per Share	Additional Paid-In Capital Issued At $38.40 Per Share	Additional Paid-In Capital Issued At $35.00 Per Share	Additional Paid-In Capital Issued At $59.10 Per Share	Additional Paid-In Capital Issued To Purchase Calando Pharmaceuticals Inc At $51.70 Per Share	Additional Paid-In Capital Issued At $57.80 Per Share	Additional Paid-In Capital Issued For Purchase Of Carbon Nanotechnologies Inc At $37.70 Per Share	Additional Paid-In Capital Issued At Approximately $18.00 Per Share Net	Additional Paid-In Capital Issued At $27.20 Per Share To Rice University	Additional Paid-In Capital Issued At $28.30 Per Share To Purchase Shares Of Unidym Inc	Additional Paid-In Capital Issued At $29.50 per Share To Purchase MASA Energy LLC	Additional Paid-In Capital Issued At $21.90 Per Share To Unidym For The Acquisition Of Nanoconduction	Additional Paid-In Capital Issued At $21.80 Per Share	Additional Paid-In Capital Issued At $5.50 Per Share To Unidym Stockholder In Exchange For Unidym's Shares	Additional Paid-In Capital Issued At $5.20 Per Share To TEL Ventures In Exchange For Unidym's Shares	Additional Paid-In Capital Issued At $3.00 Per Share	Additional Paid-In Capital Issued At $6.30 Per Share	Additional Paid-In Capital Issued At $13.12 Per Share	Additional Paid-In Capital Issued At $3.80 Per Share	Additional Paid-In Capital Issued At $3.70 Per Share	Additional Paid-In Capital Issued at $4.00 Per Share	Additional Paid-In Capital Issued @ $6.23 per share	Additional Paid-In Capital Issued @ $5.11 per share	Additional Paid-In Capital Series D Preferred Stock Issued For Subscription In Unidym	Additional Paid-In Capital Issued To Unidym Stockholders In Exchange For Unidym's Shares	Additional Paid-In Capital Issued To Calando Stockholders In Exchange For Calando's Shares	Additional Paid-In Capital Issued In Acquisition	Additional Paid-In Capital Issued Under Committed Capital Agreement	Additional Paid-In Capital Preferred Stock Issued At $1,000 Per Share	Subscription Receivable	Subscription Receivable Issued At $3.70 Per Share	Subscription Receivable Issuance Of Common Stock For Subscription	Subscription Receivable Series D Preferred Stock Issued For Subscription In Unidym	Subscription Receivable Preferred Stock Issued At $1,000 Per Share	Accumulated Deficit During The Development Stage	Accumulated Deficit During The Development Stage Issued To Unidym Stockholders In Exchange For Unidym's Shares	Noncontrolling Interest	Noncontrolling Interest Issued To Unidym Stockholders In Exchange For Unidym's Shares	Noncontrolling Interest Issued To Calando Stockholders In Exchange For Calando's Shares
Beginning Balance Amount at Sep. 30, 2002
Stock issuances		$ 3,000	$ 1,680,000																																			$ 3,000	$ 1,680																																							$ 1,678,320
Issuance and sold of Common Stock																																						300,000	168,000
Stock issuance cost charged to additional paid-in capital	(168,000)																																																																																(168,000)
Net loss attributable to Arrowhead	(95,238)																																																																																																																											(95,238)
Ending Balance Amount at Sep. 30, 2003	1,419,762																																				4,680																																								1,510,320																																															(95,238)
Beginning Balance Share at Sep. 30, 2003																																					468,000
Stock issuances			475,000	500,000	9,913,182		162,750	534,344																											(150,469)					500	6,609	163	356		475																												706						499,500	9,906,573				162,587	533,988		474,525																													(151,175)
Issuance and sold of Common Stock																																								50,000	660,879	15,000	35,623		47,500																												70,553
Stock issuance cost charged to additional paid-in capital	(96,500)																																																																												(991,318)				(96,500)
Net loss attributable to Arrowhead	(751,255)																																																																																																																											(2,528,954)		1,777,699
Stock options exercised	15,000								15,000	6,000																											75							75	6																																14,925									14,925	5,994
Stock options exercised																																					7,500							7,500	600
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Total	175,653																																																																												175,653
Ending Balance Amount at Sep. 30, 2004	11,227,149																																				13,645																																								12,059,997																																															(2,624,192)		1,777,699
Ending Balance Share at Sep. 30, 2004																																					1,363,155
Stock issuances	50,000											2,000,000																									12										502																														49,988												1,999,498
Issuance and sold of Common Stock																																					1,250										50,226
Net loss attributable to Arrowhead	(6,733,427)																																																																																																																											(6,854,918)		121,491
Stock options exercised										25,000	20,719,335																																		25	13,813																																									24,975	20,705,522
Stock options exercised																																													2,500	1,381,289
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Total	508,513																																																																												508,513
Adjustments to additional paid in capital, reallocation of noncontrolling interest	230,087																																																																												230,087
Ending Balance Amount at Sep. 30, 2005	28,026,657																																				27,997																																								35,578,580																																															(9,479,110)		1,899,190
Ending Balance Share at Sep. 30, 2005																																					2,798,419
Stock issuances	1,077,333												1,000,000	57,600	19,545,000	150,000																																205	15	5,590	25	208																																						999,795	57,585	19,539,410	149,975	1,077,125
Issuance and sold of Common Stock																																																20,485	1,500	559,000	2,536	20,838
Net loss attributable to Arrowhead	(19,961,961)																																																																																																																											(18,997,209)		(964,752)
Stock options exercised	341,537																																				116																																								341,421
Stock options exercised																																					11,579
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Total	1,369,478																																																																												1,369,478
Ending Balance Amount at Sep. 30, 2006	31,605,644																																				34,156																																								59,113,369																																															(28,476,319)		934,438
Ending Balance Share at Sep. 30, 2006																																					3,414,359
Stock issuances																	15,152,215	5,400,000																																			2,849	1,431																																									15,149,366	5,398,569
Issuance and sold of Common Stock																																																					284,945	143,122
Net loss attributable to Arrowhead	(30,712,947)																																																																																																																											(29,931,118)		(781,829)
Stock options exercised	434,727																																				186																																								434,541
Stock options exercised																																					18,616
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Total	2,175,544																																																																												2,175,544
Adjustments to additional paid in capital, reallocation of noncontrolling interest	2,401,394																																																																																	2,401,394
Ending Balance Amount at Sep. 30, 2007	26,456,577																																				38,622																																								84,672,783																																															(58,407,437)		152,609
Ending Balance Share at Sep. 30, 2007																																					3,861,042
Stock issuances																			136,000	200,000	310,000	250,000	32,700										6,960,585																						3,867	50	71	105	114	15																																					6,956,718	135,950	199,929	309,895	249,886	32,685
Issuance and sold of Common Stock																																																							386,399	5,000	7,055	10,505	11,416	1,500
Net loss attributable to Arrowhead	(27,241,639)																																																																																																																											(27,089,030)		(152,609)
Stock options exercised	290,027																																				106																																								289,921
Stock options exercised																																					10,536
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Total	3,187,397																																																																												3,187,397
Adjustments to additional paid in capital, reallocation of noncontrolling interest	1,720,962																																																																												1,720,962
Ending Balance Amount at Sep. 30, 2008	12,302,609																																				42,950																																								97,756,126																																															(85,496,467)
Ending Balance Share at Sep. 30, 2008																																					4,293,452
Stock issuances	2,758,993																							1,133,676	1,158,333																																				2,059	2,222	9,197																																								1,131,617	1,156,111	2,749,796
Issuance and sold of Common Stock																																																													205,839	222,222	919,664
Reclassification of former Unidym mezzanine debt to equity	2,000,000																																																																												2,000,000
Net loss attributable to Arrowhead	(19,308,392)																																																																																																																											(19,308,392)
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Total	2,676,170																																																																												2,676,170
Adjustments to additional paid in capital, reallocation of noncontrolling interest	16,297					2,120,250																																																																							16,297						2,120,250
Issuance of preferred stock in subsidiary																																																																																																																	300,000									(300,000)
Amortization of discount on Unidym Series D Preferred Stock																																																																																																																		163,960											(163,960)
Ending Balance Amount at Sep. 30, 2009	4,857,936																																				56,428																																								110,070,327																																										(300,000)					(104,968,819)
Beginning Balance Share at Sep. 30, 2009																																					5,641,177
Stock issuances	1,066,051																									3,222,896	3,698,671										2,251																											5,083	6,593						153	1,220					1,063,600																													3,217,813	3,692,078							(1,435)	(160,667)											200	1,282	159,447
Issuance and sold of Common Stock																																					225,189																											508,343	659,299						15,318	122,000
Net loss attributable to Arrowhead	(6,957,038)																																																																																																																											(5,774,048)		(1,182,990)
Stock options exercised																																	7,631				7																																								7,624
Stock options exercised																																					688
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Total	1,582,149																																																																												1,582,149
Adjustments to additional paid in capital, reallocation of noncontrolling interest																																	300,000																																																																																	245,345													54,655
Issuance of preferred stock in subsidiary	300,000																																																																																																																									300,000
Ending Balance Amount at Sep. 30, 2010	8,078,296																																				71,735																																								119,716,834																																															(110,742,867)		(967,406)
Ending Balance Share at Sep. 30, 2010																																					7,172,014
Stock issuances	43,279																											4,643,684									87																													14,574											43,192																															5,529,110													(900,000)
Issuance and sold of Common Stock																																					8,656																													1,458,917
Net loss attributable to Arrowhead	(3,492,399)																																																																																																																											(3,128,885)		(363,514)
Stock options exercised	13,884																																				27																																								13,857
Stock options exercised	(2,699)																																				2,700
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Total	1,404,640																																																																												1,404,640
Adjustments to additional paid in capital, reallocation of noncontrolling interest																																																																													(849,707)																																																	849,707
Issuance of preferred stock in subsidiary	1,618,509																																																																												1,618,509
Divestiture of Unidym	254,275																																																																																																																													254,275
Ending Balance Amount at Sep. 30, 2011	12,564,168																																				86,423																																								127,476,435																																										(900,000)					(113,871,752)		(226,938)
Ending Balance Share at Sep. 30, 2011																																					8,642,286
Beginning Balance Amount at Aug. 31, 2011
Issuance and sold of Common Stock																																					1,458,917
Ending Balance Amount at Sep. 30, 2011																																					86,423																																																																																		(900,000)
Ending Balance Share at Sep. 30, 2011																																					8,642,286
Issuance and sold of Common Stock																																					138,158
Ending Balance Amount at Oct. 31, 2011
Beginning Balance Amount at Sep. 30, 2011	12,564,168																																				86,423																																								127,476,435																																										(900,000)					(113,871,752)		(226,938)
Beginning Balance Share at Sep. 30, 2011																																					8,642,286
Stock issuances	40,055																											525,000	2,497,500	400,000	500,001	500,002			6,147,830	915,000	8																													1,382	6,750	1,000	83	98			9,332	689		1	40,047																															523,618	2,490,750	399,000	499,918	499,904				6,138,498	(689)	1,014,999					(100,000)
Issuance and sold of Common Stock																																					8,011																													138,158	675,000	100,000	83,211	97,831			1,217,159	68,926		1,015
Net loss attributable to Arrowhead	(16,509,974)																																																																																																																											(15,812,247)		(697,727)
Stock options exercised	23,833																																	8,000			45																																								23,788																																																	8,000
Stock options exercised	(4,583)																																				4,583
Fractional shares redeemed in reverse stock split																																					(131)
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Total	837,188																																																																												837,188
Preferred stock converted to common stock																																					276																																						(1)		(275)
Preferred stock converted to common stock, shares																																					275,782																																						(1,015)
Net income (loss) attributable to Arrowhead	(15,812,247)
Ending Balance Amount at Jun. 30, 2012	$ 8,448,603																																				$ 106,086																																								$ 139,943,181																																										$ (1,000,000)					$ (129,683,999)		$ 916,665
Ending Balance Share at Jun. 30, 2012																																					11,310,816