Securities (Tables)

6 Months Ended

Mar. 31, 2020

Marketable Securities [Abstract]

Amortized Cost, Estimated Fair Value, And Gross Unrealized Gains And Losses Of AFS Securities

The following tables reflect the amortized cost, estimated fair value, and gross unrealized gains and losses of AFS securities at the dates presented. The majority of the MBS and investment securities portfolios are composed of securities issued by United States government-sponsored enterprises ("GSEs").

	March 31, 2020
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
	(Dollars in thousands)
MBS	$	947,549	$	26,223	$	454	$	973,318
GSE debentures	250,080		699		—		250,779
Municipal bonds	11,887		53		—		11,940
	$	1,209,516	$	26,975	$	454	$	1,236,037

	September 30, 2019
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
	(Dollars in thousands)
MBS	$	923,256	$	15,571	$	2,340	$	936,487
GSE debentures	249,828		304		178		249,954
Municipal bonds	18,371		52		1		18,422
	$	1,191,455	$	15,927	$	2,519	$	1,204,863

Schedule Of Estimated Fair Value And Gross Unrealized Losses Of Securities In Continuous Unrealized Loss Position

The following tables summarize the estimated fair value and gross unrealized losses of those AFS securities on which an unrealized loss at the dates presented was reported and the continuous unrealized loss position for less than 12 months and equal to or greater than 12 months as of the dates presented.

	March 31, 2020
	Less Than 12 Months				Equal to or Greater Than 12 Months
	Estimated		Unrealized		Estimated		Unrealized
	Fair Value		Losses		Fair Value		Losses
	(Dollars in thousands)
MBS	$	53,830	$	451	$	1,985	$	3
GSE debentures	—		—		—		—
Municipal bonds	—		—		—		—
	$	53,830	$	451	$	1,985	$	3

	September 30, 2019
	Less Than 12 Months				Equal to or Greater Than 12 Months
	Estimated		Unrealized		Estimated		Unrealized
	Fair Value		Losses		Fair Value		Losses
	(Dollars in thousands)
MBS	$	111,368	$	126	$	199,442	$	2,214
GSE debentures	—		—		74,812		178
Municipal bonds	1,755		1		—		—
	$	113,123	$	127	$	274,254	$	2,392

Schedule Of Contractual Maturities

The amortized cost and estimated fair value of AFS debt securities as of March 31, 2020, by contractual maturity, are shown below.  Actual principal repayments may differ from contractual maturities due to prepayment or early call privileges by the issuer. In the case of MBS, borrowers on the underlying loans generally have the right to prepay their loans without prepayment penalty. For this reason, MBS are not included in the maturity categories.

	Amortized		Estimated
	Cost		Fair Value
	(Dollars in thousands)
One year or less	$	55,179	$	55,245
One year through five years	206,788		207,474
	261,967		262,719
MBS	947,549		973,318
	$	1,209,516	$	1,236,037

Schedule Of Taxable And Non-taxable Components Of Interest Income

The following table presents the taxable and non-taxable components of interest income on investment securities for the periods presented.

	For the Three Months Ended				For the Six Months Ended
	March 31,				March 31,
	2020		2019		2020		2019
	(Dollars in thousands)
Taxable	$	1,322	$	1,419	$	2,759	$	2,767
Non-taxable	60		86		130		179
	$	1,382	$	1,505	$	2,889	$	2,946

Schedule Of Carrying Value Of Securities Pledged As Collateral

The following table summarizes the carrying value of securities pledged as collateral for the obligations indicated below as of the dates presented.

	March 31, 2020		September 30, 2019
	(Dollars in thousands)
Federal Reserve Bank of Kansas City ("FRB of Kansas City")	$	396,458	$	6,636
Public unit deposits	321,451		381,143
Repurchase agreements	109,425		108,271
	$	827,334	$	496,050