Consolidated Statements of Operations (unaudited) - USD ($)	3 Months Ended		6 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015
Income Statement [Abstract]
REVENUE	$ 43,750	$ 43,750	$ 87,500	$ 214,500
OPERATING EXPENSES
Research and development	10,020,826	11,640,794	20,359,659	29,387,524
Acquired in-process research and development		10,142,786		10,142,786
Salaries and payroll-related costs	4,248,693	3,541,652	8,168,579	6,692,268
General and administrative expenses	3,818,335	1,696,623	5,769,944	3,782,826
Stock-based compensation	2,416,839	2,205,079	4,797,182	4,219,935
Depreciation and amortization	803,912	449,559	1,598,261	739,598
TOTAL OPERATING EXPENSES	21,308,605	29,676,493	40,693,625	54,964,937
OPERATING LOSS	(21,264,855)	(29,632,743)	(40,606,125)	(54,750,437)
OTHER INCOME (EXPENSE)
Gain (loss) on sale of fixed assets, net		45,576		19,195
Interest income (expense), net	79,060	198,113	179,440	435,530
Change in value of derivatives	369,935	168,974	346,411	2,551,116
Other income (expense)		536,087		482,902
TOTAL OTHER INCOME (EXPENSE)	448,995	948,750	525,851	3,488,743
LOSS BEFORE INCOME TAXES	(20,815,860)	(28,683,993)	(40,080,274)	(51,261,694)
NET LOSS	(20,815,860)	(28,683,993)	(40,080,274)	(51,261,694)
NET LOSS ATTRIBUTABLE TO ARROWHEAD	$ (20,815,860)	$ (28,683,993)	$ (40,080,274)	$ (51,261,694)
NET LOSS PER SHARE ATTRIBUTABLE TO ARROWHEAD SHAREHOLDERS - BASIC AND DILUTED:	$ (0.35)	$ (0.51)	$ (0.67)	$ (0.93)
Weighted average shares outstanding - basic and diluted	59,779,128	55,719,923	59,663,270	55,200,512
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX
Foreign Currency Translation Adjustments	$ 150,520	$ (63,965)	$ 196,338	$ (63,965)
COMPREHENSIVE LOSS ATTRIBUTABLE TO ARROWHEAD	$ (20,665,340)	$ (28,747,958)	$ (39,883,936)	$ (51,325,659)