Loans Receivable And Allowance For Credit Losses (Classified Loans) (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Sep. 30, 2024
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	$ 386,833	$ 639,789
Year Two	599,582	1,096,101
Year Three	1,109,648	1,372,917
Year Four	1,272,455	1,529,818
Year Five	1,459,467	827,047
Prior Years	2,956,112	2,339,984
Revolving Line of Credit	107,804	118,360
Revolving Line of Credit Converted to Term Loan	7,974	6,357
Total Amortized Cost	7,899,875	7,930,373
One- to Four-Family Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	108,626	242,563
Year Two	239,370	652,822
Year Three	628,095	1,063,977
Year Four	1,023,569	1,383,986
Year Five	1,331,081	749,865
Prior Years	2,798,139	2,223,566
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	6,128,880	6,316,779
One- to Four-Family Segment [Member] \| Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	3,866,343	3,950,046
One- to Four-Family Segment [Member] \| Originated [Member] \| Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	108,626	241,765
Year Two	238,584	325,492
Year Three	311,276	578,275
Year Four	556,375	809,643
Year Five	777,713	521,647
Prior Years	1,852,621	1,447,237
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	3,845,195	3,924,059
One- to Four-Family Segment [Member] \| Originated [Member] \| Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	0
Year Two	0	295
Year Three	1,161	1,229
Year Four	1,005	1,982
Year Five	843	772
Prior Years	5,966	9,565
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	8,975	13,843
One- to Four-Family Segment [Member] \| Originated [Member] \| Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	0
Year Two	0	658
Year Three	482	49
Year Four	84	468
Year Five	214	1,398
Prior Years	11,393	9,571
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	12,173	12,144
One- to Four-Family Segment [Member] \| Correspondent Purchased [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	2,142,220	2,239,143
One- to Four-Family Segment [Member] \| Correspondent Purchased [Member] \| Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	798
Year Two	786	325,384
Year Three	313,915	482,103
Year Four	465,188	570,970
Year Five	551,402	225,650
Prior Years	802,496	623,496
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	2,133,787	2,228,401
One- to Four-Family Segment [Member] \| Correspondent Purchased [Member] \| Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	0
Year Two	0	993
Year Three	986	659
Year Four	513	658
Year Five	371	398
Prior Years	948	977
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	2,818	3,685
One- to Four-Family Segment [Member] \| Correspondent Purchased [Member] \| Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	0
Year Two	0	0
Year Three	275	1,662
Year Four	404	265
Year Five	538	0
Prior Years	4,398	5,130
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	5,615	7,057
One- to Four-Family Segment [Member] \| Bulk Purchased [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	120,317	127,590
One- to Four-Family Segment [Member] \| Bulk Purchased [Member] \| Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	0
Year Two	0	0
Year Three	0	0
Year Four	0	0
Year Five	0	0
Prior Years	117,765	124,076
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	117,765	124,076
One- to Four-Family Segment [Member] \| Bulk Purchased [Member] \| Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	0
Year Two	0	0
Year Three	0	0
Year Four	0	0
Year Five	0	0
Prior Years	0	0
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	0	0
One- to Four-Family Segment [Member] \| Bulk Purchased [Member] \| Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	0
Year Two	0	0
Year Three	0	0
Year Four	0	0
Year Five	0	0
Prior Years	2,552	3,514
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	2,552	3,514
Commercial Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	272,487	385,703
Year Two	351,211	436,131
Year Three	475,613	302,624
Year Four	243,525	144,010
Year Five	126,782	76,263
Prior Years	155,395	114,172
Revolving Line of Credit	37,195	44,829
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	1,662,208	1,503,732
Commercial Segment [Member] \| Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	1,526,318	1,374,054
Commercial Segment [Member] \| Commercial Real Estate [Member] \| Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	250,522	326,158
Year Two	312,139	400,649
Year Three	404,683	284,493
Year Four	227,779	135,935
Year Five	120,081	74,174
Prior Years	149,210	110,309
Revolving Line of Credit	7,591	23,865
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	1,472,005	1,355,583
Commercial Segment [Member] \| Commercial Real Estate [Member] \| Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	8,270	12,440
Year Two	0	2,543
Year Three	0	0
Year Four	0	0
Year Five	0	92
Prior Years	82	1,094
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	8,352	16,169
Commercial Segment [Member] \| Commercial Real Estate [Member] \| Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	142
Year Two	142	827
Year Three	42,008	0
Year Four	0	0
Year Five	111	647
Prior Years	3,650	636
Revolving Line of Credit	50	50
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	45,961	2,302
Commercial Segment [Member] \| Commercial and Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	135,890	129,678
Commercial Segment [Member] \| Commercial and Industrial [Member] \| Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	13,600	46,335
Year Two	38,513	32,112
Year Three	28,892	18,131
Year Four	15,581	8,075
Year Five	6,590	1,350
Prior Years	2,371	2,051
Revolving Line of Credit	28,390	20,876
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	133,937	128,930
Commercial Segment [Member] \| Commercial and Industrial [Member] \| Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	95	401
Year Two	190	0
Year Three	30	0
Year Four	58	0
Year Five	0	0
Prior Years	0	0
Revolving Line of Credit	526	12
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	899	413
Commercial Segment [Member] \| Commercial and Industrial [Member] \| Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	227
Year Two	227	0
Year Three	0	0
Year Four	107	0
Year Five	0	0
Prior Years	82	82
Revolving Line of Credit	638	26
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	1,054	335
Consumer Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	5,720	11,523
Year Two	9,001	7,148
Year Three	5,940	6,316
Year Four	5,361	1,822
Year Five	1,604	919
Prior Years	2,578	2,246
Revolving Line of Credit	70,609	73,531
Revolving Line of Credit Converted to Term Loan	7,974	6,357
Total Amortized Cost	108,787	109,862
Consumer Segment [Member] \| Home Equity [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	99,353	100,247
Consumer Segment [Member] \| Home Equity [Member] \| Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	2,988	7,331
Year Two	6,107	4,377
Year Three	4,047	4,575
Year Four	4,143	1,437
Year Five	1,337	814
Prior Years	2,483	2,127
Revolving Line of Credit	69,870	73,020
Revolving Line of Credit Converted to Term Loan	7,760	5,895
Total Amortized Cost	98,735	99,576
Consumer Segment [Member] \| Home Equity [Member] \| Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	0
Year Two	35	0
Year Three	20	0
Year Four	0	0
Year Five	0	0
Prior Years	0	0
Revolving Line of Credit	0	45
Revolving Line of Credit Converted to Term Loan	107	281
Total Amortized Cost	162	326
Consumer Segment [Member] \| Home Equity [Member] \| Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	0
Year Two	0	20
Year Three	0	0
Year Four	0	0
Year Five	0	0
Prior Years	9	24
Revolving Line of Credit	340	120
Revolving Line of Credit Converted to Term Loan	107	181
Total Amortized Cost	456	345
Consumer Segment [Member] \| Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	9,434	9,615
Consumer Segment [Member] \| Other [Member] \| Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	2,732	4,112
Year Two	2,809	2,737
Year Three	1,859	1,697
Year Four	1,175	385
Year Five	267	101
Prior Years	84	95
Revolving Line of Credit	398	346
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	9,324	9,473
Consumer Segment [Member] \| Other [Member] \| Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	0
Year Two	0	0
Year Three	0	0
Year Four	0	0
Year Five	0	0
Prior Years	0	0
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	0	0
Consumer Segment [Member] \| Other [Member] \| Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	80
Year Two	50	14
Year Three	14	44
Year Four	43	0
Year Five	0	4
Prior Years	2	0
Revolving Line of Credit	1	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	$ 110	$ 142

Amortized cost excluding accrued interest, before allowance for credit loss, of financing receivable. Excludes net investment in lease.

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