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Securities - Summarizes Amortized Cost and Estimated Fair Values of Securities Available for Sale (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 456,476
Gross Unrealized Gains	6,369
Gross Unrealized Losses	(418)
Estimated Fair Value, Total	462,427
U.S. Federal agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	359,076
Gross Unrealized Gains	2,043
Gross Unrealized Losses	(215)
Estimated Fair Value, Total	360,904
Mortgage backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	33,336
Gross Unrealized Gains	620
Gross Unrealized Losses
Estimated Fair Value, Total	33,956	22,390
States and political subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	52,013
Gross Unrealized Gains	1,436
Gross Unrealized Losses	(63)
Estimated Fair Value, Total	53,386	57,829
Other securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	12,051
Gross Unrealized Gains	2,270
Gross Unrealized Losses	(140)
Estimated Fair Value, Total	$ 14,181	$ 10,356

X

- Definition

Amount of accumulated pre-tax unrealized gain before deducting pre-tax unrealized losses on investments in available-for-sale securities impacting investments.

+ References

No definition available.

+ Details

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X

- Definition

Amount of accumulated pre-tax unrealized loss before deducting pre-tax unrealized gain on investments in available-for-sale securities impacting investments.

+ References

No definition available.

+ Details

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X

- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 5

-Subparagraph (aa)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562

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X

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.2)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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