Employee Benefit Plans - Additional Information (Detail) (USD $)	12 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Schedule of Employee Benefit Plans [Line Items]
Employer matching contribution	$ 1,747,000	$ 1,521,000	$ 1,366,000
Maximum Employer Matching Contribution, Percent of participant's Gross salary	6.00%	6.00%	6.00%
Employer Matching Contribution, Percent of Match	100.00%	100.00%	100.00%

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

No definition available.

Name:	us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration