Summary of Activity Related to Target Number of Shares Awarded and Actual Number of Shares Earned Under 2007 Plan (Detail) (2007 Plan, USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended
	Mar. 31, 2013
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Line Items]
Beginning Balance, Outstanding number of shares	158
Shares awarded, Number of shares award forfeited (various awards)	(31)
Ending Balance, Outstanding number of shares	161
Beginning Balance, Outstanding weighted average fair value at date of grant	$ 18.30
Shares not earned, Weighted average fair value at date of grant awards forfeited (various awards)	$ 17.01
Ending Balance, Outstanding weighted average fair value at date of grant	$ 17.81
Restricted shares
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Line Items]
Shares awarded, Number of shares	12
Shares earned, Number of shares	(5)
Shares earned, Weighted average fair value at date of grant	$ 15.50
Shares not earned, Weighted average fair value at date of grant	$ 22.00
Performance shares
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Line Items]
Shares awarded, Number of shares	60
Shares earned, Number of shares	(33)
Shares earned, Weighted average fair value at date of grant	$ 15.98
Shares not earned, Weighted average fair value at date of grant	$ 16.05