Investment Securities - Summary of Amortized Cost and Fair Value of Investment Securities Available for Sale (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Sep. 30, 2013
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Amortized Cost	$ 372,565	$ 315,515
Available for Sale, Gross Unrealized Gains	5,594	4,361
Available for Sale, Gross Unrealized Losses	(3,135)	(4,254)
Available for Sale, Fair Value	375,024	315,622
Fannie Mae [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Amortized Cost	141,678	114,927
Available for Sale, Gross Unrealized Gains	1,991	1,691
Available for Sale, Gross Unrealized Losses	(1,230)	(1,595)
Available for Sale, Fair Value	142,439	115,023
Freddie Mac [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Amortized Cost	80,805	60,111
Available for Sale, Gross Unrealized Gains	813	838
Available for Sale, Gross Unrealized Losses	(1,017)	(1,252)
Available for Sale, Fair Value	80,601	59,697
Governmental National Mortgage Association [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Amortized Cost	31,709	39,692
Available for Sale, Gross Unrealized Gains	170	289
Available for Sale, Gross Unrealized Losses	(170)	(230)
Available for Sale, Fair Value	31,709	39,751
Other Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Amortized Cost	2,839	3,385
Available for Sale, Gross Unrealized Losses	(7)	(19)
Available for Sale, Fair Value	2,832	3,366
Total Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Amortized Cost	257,031	218,115
Available for Sale, Gross Unrealized Gains	2,974	2,818
Available for Sale, Gross Unrealized Losses	(2,424)	(3,096)
Available for Sale, Fair Value	257,581	217,837
Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Amortized Cost	42,067	23,754
Available for Sale, Gross Unrealized Gains	1,390	654
Available for Sale, Gross Unrealized Losses	(294)	(499)
Available for Sale, Fair Value	43,163	23,909
U.S. Government Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Amortized Cost	48,037	52,775
Available for Sale, Gross Unrealized Gains	240	225
Available for Sale, Gross Unrealized Losses	(372)	(480)
Available for Sale, Fair Value	47,905	52,520
Corporate Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Amortized Cost	13,169	12,756
Available for Sale, Gross Unrealized Gains	262	186
Available for Sale, Gross Unrealized Losses	(26)	(169)
Available for Sale, Fair Value	13,405	12,773
Trust-Preferred Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Amortized Cost	5,003	4,943
Available for Sale, Gross Unrealized Gains	688	471
Available for Sale, Fair Value	5,691	5,414
Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Amortized Cost	5,233	1,147
Available for Sale, Gross Unrealized Gains	40	7
Available for Sale, Gross Unrealized Losses	(19)
Available for Sale, Fair Value	5,254	1,154
Total Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Amortized Cost	370,540	313,490
Available for Sale, Gross Unrealized Gains	5,594	4,361
Available for Sale, Gross Unrealized Losses	(3,135)	(4,244)
Available for Sale, Fair Value	372,999	313,607
Equity Securities-Financial Services [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Amortized Cost	2,025	2,025
Available for Sale, Gross Unrealized Losses		(10)
Available for Sale, Fair Value	$ 2,025	$ 2,015