Loans Receivable And Allowance For Credit Losses (Delinquent Loans) (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	$ 639,789	$ 1,124,730
Year Two	1,096,101	1,450,679
Year Three	1,372,917	1,709,273
Year Four	1,529,818	904,106
Year Five	827,047	403,494
Prior Years	2,339,984	2,285,008
Revolving Line of Credit	118,360	110,969
Revolving Line of Credit Converted to Term Loan	6,357	6,449
Total Amortized Cost	7,930,373	7,994,708
Financial Asset, Not Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	7,904,743	7,969,425
Financial Asset, 30 to 89 Days Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	16,049	16,347
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	9,581	8,936
One- to Four-Family Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	242,563	665,253
Year Two	652,822	1,117,986
Year Three	1,063,977	1,485,849
Year Four	1,383,986	817,322
Year Five	749,865	317,676
Prior Years	2,223,566	2,202,364
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	6,316,779	6,606,450
One- to Four-Family Segment [Member] | Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	3,950,046	4,033,028
One- to Four-Family Segment [Member] | Originated [Member] | Financial Asset, Not Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	241,765	318,211
Year Two	326,211	598,283
Year Three	578,430	875,563
Year Four	811,455	567,975
Year Five	521,550	253,546
Prior Years	1,459,500	1,407,090
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	3,938,911	4,020,668
One- to Four-Family Segment [Member] | Originated [Member] | Financial Asset, 30 to 89 Days Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	358
Year Two	64	898
Year Three	1,074	644
Year Four	638	1,437
Year Five	1,666	820
Prior Years	5,422	5,960
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	8,864	10,117
One- to Four-Family Segment [Member] | Originated [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	292
Year Two	170	155
Year Three	49	0
Year Four	0	0
Year Five	601	209
Prior Years	1,451	1,587
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	2,271	2,243
One- to Four-Family Segment [Member] | Correspondent Purchased [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	2,239,143	2,435,750
One- to Four-Family Segment [Member] | Correspondent Purchased [Member] | Financial Asset, Not Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	798	346,084
Year Two	326,377	518,650
Year Three	482,598	608,573
Year Four	571,182	247,346
Year Five	226,048	62,652
Prior Years	624,961	643,739
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	2,231,964	2,427,044
One- to Four-Family Segment [Member] | Correspondent Purchased [Member] | Financial Asset, 30 to 89 Days Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	308
Year Two	0	0
Year Three	164	1,069
Year Four	446	564
Year Five	0	449
Prior Years	2,479	2,862
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	3,089	5,252
One- to Four-Family Segment [Member] | Correspondent Purchased [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	0
Year Two	0	0
Year Three	1,662	0
Year Four	265	0
Year Five	0	0
Prior Years	2,163	3,454
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	4,090	3,454
One- to Four-Family Segment [Member] | Bulk Purchased [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	127,590	137,672
One- to Four-Family Segment [Member] | Bulk Purchased [Member] | Financial Asset, Not Past Due [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	125,982	136,577
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	125,982	136,577
One- to Four-Family Segment [Member] | Bulk Purchased [Member] | Financial Asset, 30 to 89 Days Past Due [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	69	153
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	69	153
One- to Four-Family Segment [Member] | Bulk Purchased [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [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	1,539	942
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	1,539	942
Commercial Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	385,703	449,216
Year Two	436,131	324,330
Year Three	302,624	220,682
Year Four	144,010	85,373
Year Five	76,263	84,939
Prior Years	114,172	80,255
Revolving Line of Credit	44,829	38,251
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	1,503,732	1,283,046
Commercial Segment [Member] | Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	1,374,054	1,170,116
Commercial Segment [Member] | Commercial Real Estate [Member] | Financial Asset, Not Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	338,511	404,867
Year Two	403,193	301,164
Year Three	284,493	208,942
Year Four	135,932	81,478
Year Five	74,266	82,027
Prior Years	110,448	79,188
Revolving Line of Credit	23,055	10,448
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	1,369,898	1,168,114
Commercial Segment [Member] | Commercial Real Estate [Member] | Financial Asset, 30 to 89 Days Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	229	36
Year Two	807	0
Year Three	0	0
Year Four	3	0
Year Five	0	0
Prior Years	1,094	0
Revolving Line of Credit	860	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	2,993	36
Commercial Segment [Member] | Commercial Real Estate [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	916
Year Two	19	0
Year Three	0	0
Year Four	0	594
Year Five	647	219
Prior Years	497	237
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	1,163	1,966
Commercial Segment [Member] | Commercial and Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	129,678	112,930
Commercial Segment [Member] | Commercial and Industrial [Member] | Financial Asset, Not Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	46,736	43,397
Year Two	32,112	23,166
Year Three	17,990	11,740
Year Four	8,052	3,228
Year Five	1,350	2,690
Prior Years	2,051	748
Revolving Line of Credit	20,914	27,684
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	129,205	112,653
Commercial Segment [Member] | Commercial and Industrial [Member] | Financial Asset, 30 to 89 Days Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	227	0
Year Two	0	0
Year Three	141	0
Year Four	23	0
Year Five	0	2
Prior Years	0	0
Revolving Line of Credit	0	57
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	391	59
Commercial Segment [Member] | Commercial and Industrial [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	0
Year Two	0	0
Year Three	0	0
Year Four	0	73
Year Five	0	1
Prior Years	82	82
Revolving Line of Credit	0	62
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	82	218
Consumer Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	11,523	10,261
Year Two	7,148	8,363
Year Three	6,316	2,742
Year Four	1,822	1,411
Year Five	919	879
Prior Years	2,246	2,389
Revolving Line of Credit	73,531	72,718
Revolving Line of Credit Converted to Term Loan	6,357	6,449
Total Amortized Cost	109,862	105,212
Consumer Segment [Member] | Home Equity [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	100,247	95,955
Consumer Segment [Member] | Home Equity [Member] | Financial Asset, Not Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	7,331	5,428
Year Two	4,378	5,631
Year Three	4,540	1,955
Year Four	1,437	990
Year Five	814	746
Prior Years	2,133	2,195
Revolving Line of Credit	72,721	71,986
Revolving Line of Credit Converted to Term Loan	6,084	6,312
Total Amortized Cost	99,438	95,243
Consumer Segment [Member] | Home Equity [Member] | Financial Asset, 30 to 89 Days Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	73
Year Two	0	39
Year Three	35	0
Year Four	0	79
Year Five	0	0
Prior Years	0	50
Revolving Line of Credit	349	239
Revolving Line of Credit Converted to Term Loan	87	125
Total Amortized Cost	471	605
Consumer Segment [Member] | Home Equity [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	0
Year Two	19	0
Year Three	0	0
Year Four	0	0
Year Five	0	0
Prior Years	18	15
Revolving Line of Credit	115	81
Revolving Line of Credit Converted to Term Loan	186	11
Total Amortized Cost	338	107
Consumer Segment [Member] | Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	9,615	9,257
Consumer Segment [Member] | Other [Member] | Financial Asset, Not Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	4,109	4,737
Year Two	2,728	2,613
Year Three	1,641	765
Year Four	327	338
Year Five	101	132
Prior Years	95	129
Revolving Line of Credit	344	412
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	9,345	9,126
Consumer Segment [Member] | Other [Member] | Financial Asset, 30 to 89 Days Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	3	17
Year Two	9	80
Year Three	100	22
Year Four	58	4
Year Five	0	1
Prior Years	0	0
Revolving Line of Credit	2	0
Revolving Line of Credit Converted to Term Loan	0	1
Total Amortized Cost	172	125
Consumer Segment [Member] | Other [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	80	6
Year Two	14	0
Year Three	0	0
Year Four	0	0
Year Five	4	0
Prior Years	0	0
Revolving Line of Credit	0	0
Revolving Line of Credit Converted to Term Loan	0	0
Total Amortized Cost	$ 98	$ 6