Employee Benefits - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of employers contribution as percentage of employees contribution	50.00%
A maximum percentage of employers contribution on eligible compensation	3.00%
Discretionary and matching contributions to plan	$ 1,539	$ 2,033	$ 637
Number of active stock-based compensation plan	2
Minimum rate of payroll deduction	1.00%
Maximum rate of payroll deduction	15.00%
Additional rate of match by Meridian	5.00%
Options granted	66,000
Options granted, authorizing limit	3,553,000
Rate of exercise price of underlying common shares	100.00%
Weighted average grant-date fair value of options granted	$ 4.19	$ 4.68	$ 4.97
Measurement dates for ratably earning one-third of the grant		21 months
Measurement dates for ratably earning one-third of the grant, period two		33 months
Measurement dates for ratably earning one-third of the grant, period three		45 months
Weighted average remaining vesting period	1 year 9 months
Number of restricted share units vested	15
Stock based compensation	2,502	1,987	2,614
Total income tax benefit recognized in stock-based compensation arrangements	850	588	865
Stock Compensation Expense expected period for recognition	2014 through 2017
Number of executive officers granted unrestricted common shares	2
Stock compensation expense to adjust estimated forfeiture rates to actual	93	73	39
Total intrinsic value of options exercised	2,483	452	8,038
Total grant-date fair value of options that vested	712	361	1,594
Cash received from options exercised	2,258	431	1,721
Tax benefits realized and recorded to additional paid-in capital from option exercises	306	15	1,256
Restricted Stock Units and Restricted Stock Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Shares	204,000	210,000	214,000
Weighted-average grant date fair value of restricted share units	$ 19.38	$ 17.99	$ 22.93
Granted, additional Shares		110,000
Weighted-average grant date fair value of restricted share units, additional		$ 17.57
Ratable earnings in equal installments		one-third
Restricted shares and restricted share units outstanding	450,000
Weighted average grant date fair value of outstanding restricted shares and restricted share units	$ 19.92
Intrinsic value of restricted shares and restricted share units	10,704
Weighted-average grant date fair value of restricted share units	$ 21.76
Stock based compensation	2,069	1,561	2,009
Stock based compensation	1,959
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted		1,035,000
Weighted average grant-date fair value of options granted		$ 4.66
Stock based compensation	336	426	495
Stock based compensation	191
Unrestricted Common Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation	$ 97		$ 110
2004 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for grant			3,000,000
Options granted	2,256,000
Maximum terms	10 years
2012 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for grant			3,000,000
Options granted	191,000