Investment Securities (Additional Information) (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Sep. 30, 2014
Investment Securities [Line Items]
Net gain on trading account securities	$ 45,000	$ 210,000	$ 205,000	$ 572,000
Net realized gain on trading account securities	34,000	159,000	194,000	577,000
Trading Securities, Unrealized Holding Gain	$ 11,000	51,000	$ 11,000
Trading Securities, Unrealized Holding Loss				5,000
Weighted Average Yield Of Available For Sale Securities In Loss Positions	2.47%		2.47%
Weighted Average Coupon Rate Available For Sale Securities In Loss Positions	3.28%		3.28%
Gain (Loss) On Sale Of Securities, Net	$ 0	$ 122,000	$ 0	$ 123,000
Trading Securities, Total	$ 8,770,000		$ 8,770,000		$ 5,319,000
Debt Securities
Investment Securities [Line Items]
Available for sale debt securities in loss position, depreciation percentage	1.50%		1.50%
Debt Securities | Downgraded Due To Potential Credit Losses
Investment Securities [Line Items]
Downgraded due to potential credit losses	$ 2,700,000		$ 2,700,000
Debt Securities | Downgraded Privately Issued CMOs
Investment Securities [Line Items]
Fair market value of downgraded privately-issued CMOs	$ 3,900,000		$ 3,900,000