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Amount of unamortized loan commitment, origination, and other costs (fees) on financing receivable recognized as adjustment to yield. Excludes financing receivable covered under loss sharing agreement.

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Loans Receivable And Allowance For Credit Losses (Summary Of Loans Receivable) (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Mar. 31, 2026	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Sep. 30, 2024
Loans Receivable [Line Items]
Loans receivable, gross	$ 8,192,739		$ 8,133,875
ACL	26,103	$ 26,599	24,039	$ 22,808	$ 23,970	$ 23,035
Deferred loan fees/discounts	30,508		31,268
Premiums/deferred costs	(30,634)		(33,393)
Loans receivable, net	8,166,762		8,111,961
One- to Four-Family Segment [Member]
Loans Receivable [Line Items]
Loans receivable, gross	5,602,256		5,904,635
ACL	2,224	2,663	3,046	3,532	3,562	3,673
One- to Four-Family Segment [Member] \| Originated [Member]
Loans Receivable [Line Items]
Loans receivable, gross	3,642,458		3,774,134
One- to Four-Family Segment [Member] \| Correspondent Purchased [Member]
Loans Receivable [Line Items]
Loans receivable, gross	1,844,014		2,000,216
One- to Four-Family Segment [Member] \| Bulk Purchased [Member]
Loans Receivable [Line Items]
Loans receivable, gross	105,210		114,231
One- to Four-Family Segment [Member] \| Construction [Member]
Loans Receivable [Line Items]
Loans receivable, gross	10,574		16,054
Commercial Segment [Member]
Loans Receivable [Line Items]
Loans receivable, gross	2,472,975		2,115,995
ACL	23,696	23,735	20,776	19,039	20,176	19,154
Commercial Segment [Member] \| Construction [Member]
Loans Receivable [Line Items]
Loans receivable, gross	193,480		195,886
Commercial Segment [Member] \| Commercial Real Estate [Member]
Loans Receivable [Line Items]
Loans receivable, gross	2,005,641		1,709,990
ACL	20,886	21,689	18,277	16,598	19,005	17,968
Commercial Segment [Member] \| Commercial and Industrial [Member]
Loans Receivable [Line Items]
Loans receivable, gross	273,854		210,119
ACL	2,810	2,046	2,499	2,441	1,171	1,186
Consumer Segment [Member]
Loans Receivable [Line Items]
Loans receivable, gross	117,508		113,245
ACL	183	$ 201	217	$ 237	$ 232	$ 208
Consumer Segment [Member] \| Home Equity [Member]
Loans Receivable [Line Items]
Loans receivable, gross	110,372		104,809
Consumer Segment [Member] \| Other [Member]
Loans Receivable [Line Items]
Loans receivable, gross	$ 7,136		$ 8,436