Loans Receivable And Allowance For Credit Losses (Classified Loans) (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Sep. 30, 2024
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	$ 778,885	$ 639,789
Year Two	566,201	1,096,101
Year Three	1,069,855	1,372,917
Year Four	1,245,856	1,529,818
Year Five	1,417,974	827,047
Prior Years	2,854,036	2,339,984
Revolving Line of Credit	105,461	118,360
Revolving Line of Credit Converted to Term Loan	8,094	6,357
Total Amortized Cost	8,046,362	7,930,373
One- to Four-Family Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	175,465	242,563
Year Two	238,334	652,822
Year Three	613,819	1,063,977
Year Four	999,071	1,383,986
Year Five	1,297,656	749,865
Prior Years	2,704,513	2,223,566
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	6,028,858	6,316,779
One- to Four-Family Segment [Member] | Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	3,828,903	3,950,046
One- to Four-Family Segment [Member] | Originated [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	175,465	241,765
Year Two	237,821	325,492
Year Three	301,776	578,275
Year Four	544,279	809,643
Year Five	756,649	521,647
Prior Years	1,789,116	1,447,237
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	3,805,106	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	1,394	1,229
Year Four	781	1,982
Year Five	1,706	772
Prior Years	6,168	9,565
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	10,049	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	1,656	49
Year Four	568	468
Year Five	323	1,398
Prior Years	11,201	9,571
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	13,748	12,144
One- to Four-Family Segment [Member] | Correspondent Purchased [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	2,082,861	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	513	325,384
Year Three	308,011	482,103
Year Four	452,304	570,970
Year Five	538,342	225,650
Prior Years	775,638	623,496
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	2,074,808	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	982	659
Year Four	523	658
Year Five	368	398
Prior Years	661	977
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	2,534	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	0	1,662
Year Four	616	265
Year Five	268	0
Prior Years	4,635	5,130
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	5,519	7,057
One- to Four-Family Segment [Member] | Bulk Purchased [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	117,094	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	114,837	124,076
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	114,837	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	2,257	3,514
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	2,257	3,514
Commercial Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	595,519	385,703
Year Two	319,605	436,131
Year Three	450,597	302,624
Year Four	241,816	144,010
Year Five	118,905	76,263
Prior Years	147,155	114,172
Revolving Line of Credit	30,897	44,829
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	1,904,494	1,503,732
Commercial Segment [Member] | Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	1,720,372	1,374,054
Commercial Segment [Member] | Commercial Real Estate [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	463,559	326,158
Year Two	291,605	400,649
Year Three	381,668	284,493
Year Four	226,907	135,935
Year Five	112,744	74,174
Prior Years	141,934	110,309
Revolving Line of Credit	9,073	23,865
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	1,627,490	1,355,583
Commercial Segment [Member] | Commercial Real Estate [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	8,030	12,440
Year Two	0	2,543
Year Three	0	0
Year Four	0	0
Year Five	0	92
Prior Years	81	1,094
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	8,111	16,169
Commercial Segment [Member] | Commercial Real Estate [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	39,962	142
Year Two	142	827
Year Three	41,548	0
Year Four	0	0
Year Five	108	647
Prior Years	2,961	636
Revolving Line of Credit	50	50
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	84,771	2,302
Commercial Segment [Member] | Commercial and Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	184,122	129,678
Commercial Segment [Member] | Commercial and Industrial [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	83,689	46,335
Year Two	27,631	32,112
Year Three	27,355	18,131
Year Four	14,761	8,075
Year Five	6,053	1,350
Prior Years	2,097	2,051
Revolving Line of Credit	20,453	20,876
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	182,039	128,930
Commercial Segment [Member] | Commercial and Industrial [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	279	401
Year Two	0	0
Year Three	26	0
Year Four	51	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	882	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	97	0
Year Five	0	0
Prior Years	82	82
Revolving Line of Credit	795	26
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	1,201	335
Consumer Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	7,901	11,523
Year Two	8,262	7,148
Year Three	5,439	6,316
Year Four	4,969	1,822
Year Five	1,413	919
Prior Years	2,368	2,246
Revolving Line of Credit	74,564	73,531
Revolving Line of Credit Converted to Term Loan	8,094	6,357
Total Amortized Cost	113,010	109,862
Consumer Segment [Member] | Home Equity [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	103,901	100,247
Consumer Segment [Member] | Home Equity [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	4,443	7,331
Year Two	5,994	4,377
Year Three	3,813	4,575
Year Four	3,906	1,437
Year Five	1,180	814
Prior Years	2,292	2,127
Revolving Line of Credit	73,800	73,020
Revolving Line of Credit Converted to Term Loan	7,887	5,895
Total Amortized Cost	103,315	99,576
Consumer Segment [Member] | Home Equity [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	0
Year Two	0	0
Year Three	20	0
Year Four	0	0
Year Five	0	0
Prior Years	0	0
Revolving Line of Credit	257	45
Revolving Line of Credit Converted to Term Loan	88	281
Total Amortized Cost	365	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	11	24
Revolving Line of Credit	91	120
Revolving Line of Credit Converted to Term Loan	119	181
Total Amortized Cost	221	345
Consumer Segment [Member] | Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	9,109	9,615
Consumer Segment [Member] | Other [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	3,449	4,112
Year Two	2,231	2,737
Year Three	1,592	1,697
Year Four	1,021	385
Year Five	233	101
Prior Years	65	95
Revolving Line of Credit	416	346
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	9,007	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	9	80
Year Two	37	14
Year Three	14	44
Year Four	42	0
Year Five	0	4
Prior Years	0	0
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	$ 102	$ 142