XML 26 R57.htm IDEA: XBRL DOCUMENT v2.4.0.6

Related Party Transactions - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended
	Aug. 31, 2010	Sep. 30, 2012	Sep. 30, 2011
Related Party Transaction [Line Items]
Monthly remuneration of employee	$ 10,000
Remuneration of Vincent Anzalone		$ 120,000	$ 120,000
Nanotope, Inc [Member]
Related Party Transaction [Line Items]
Shares owned by Arrowhead's President and CEO		1,395,900
Percentage of outstanding voting securities owned by Arrowhead's President and CEO		14.20%

X

- Definition

Monthly remuneration of employee.

+ References

No definition available.

+ Details

Name:	arwr_MonthlyRemunerationOfEmployee
Namespace Prefix:	arwr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Percentage shares owned by employee.

+ References

No definition available.

+ Details

Name:	arwr_PercentageSharesOwnedByEmployee
Namespace Prefix:	arwr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Remuneration.

+ References

No definition available.

+ Details

Name:	arwr_RemunerationPaid
Namespace Prefix:	arwr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Shares owned employee.

+ References

No definition available.

+ Details

Name:	arwr_SharesOwnedByEmployee
Namespace Prefix:	arwr_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_RelatedPartyTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration