Stock-Based Compensation - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, vesting period (in years)			10 years
2007 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, vesting period (in years)			10 years
Aggregate number of shares that may be awarded	600,000		600,000
Performance period (in years)			3 years
Stock options may be awarded (in shares)	290,000		290,000
Compensation expense related to performance and restricted shares awarded	$ 498	$ 148	$ 1,051	$ 515
Total unrecognized compensation cost related to performance and restricted shares awarded	$ 2,514		$ 2,514
Period of recognized compensation cost (in years)			2 years 3 months
2007 Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares earned as percentage of initial target number shares awarded			150.00%
Outstanding share awards earned and issued at greater than the target number of shares			150.00%
Performance shares | 2007 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, vesting period (in years)			3 years
Awards forfeited (in shares)			45,000
Shares forfeited fair value (in dollars per share)			$ 16.03
Additional shares granted (in shares)			43,000
Additional shares granted fair value (in dollars per share)			$ 26.50
Additional shares granted, vesting period			2 years
Share granted (in shares)			68,000
Granted shares fair value (in dollars per share)			$ 26.50
Restricted shares | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, vesting period (in years)			1 year
Restricted shares | 2007 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, vesting period (in years)			1 year
Additional shares granted (in shares)			10,000
Additional shares granted fair value (in dollars per share)			$ 31.12
Share granted (in shares)			18,000
Granted shares fair value (in dollars per share)			$ 22.02