Stock-Based Compensation - Summary of Option Activity under Stock-Based Compensation Plan (Detail) (USD $)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
2009 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Options exercised	(1,500)
Number of Shares, Options outstanding	316,500	318,000	318,000
Average Exercise Price Per Share, Options exercised	$ 7.689
Average Exercise Price Per Share, Options outstanding	$ 7.655	$ 7.655	$ 7.655
1997 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Options outstanding	27,500	27,500	27,500
Average Exercise Price Per Share, Options outstanding	$ 9.32	$ 9.32	$ 9.32