Commitments and Contingencies - Additional Information (Detail) (USD $)	12 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Operating Lease Obligations [Line Items]
Rental expense under operating leases with initial terms exceeding one year	$ 900,000	$ 805,000	$ 717,000
Letter of Credit
Operating Lease Obligations [Line Items]
Unused letters of credit, total	$ 580,000

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

No definition available.

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant