Investment Securities (Investments Securities Available For Sale) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Schedule of Available For Sale Securities [Line Items]
Investments securities available for sale, Amortized Cost	$ 532,812	$ 550,605
Available-for-sale securities, gross unrealized gain	12,678	1,643
Available-for-sale securities, gross unrealized losses	(6)	(4,384)
Available-for-sale Securities	545,484	547,864
REMIC's
Schedule of Available For Sale Securities [Line Items]
Investments securities available for sale, Amortized Cost	526,522	544,042
Available-for-sale securities, gross unrealized gain	12,387	1,384
Available-for-sale securities, gross unrealized losses	(6)	(4,384)
Available-for-sale Securities	538,903	541,042
Fannie Mae Certificates
Schedule of Available For Sale Securities [Line Items]
Investments securities available for sale, Amortized Cost	6,290	6,563
Available-for-sale securities, gross unrealized gain	291	259
Available-for-sale securities, gross unrealized losses	0	0
Available-for-sale Securities	$ 6,581	$ 6,822

Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

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

+ References

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

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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.

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