Loans Receivable And Allowance For Credit Losses (Classified Loans) (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	$ 1,475,411	$ 1,953,147
Year Two	1,824,711	1,204,963
Year Three	1,019,694	520,852
Year Four	445,538	455,353
Year Five	362,766	485,640
Prior Years	2,254,177	2,388,212
Revolving Line of Credit	98,282	92,798
Total Amortized Cost	7,480,579	7,100,965
One- to Four-Family Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	1,058,519	1,590,219
Year Two	1,581,839	1,041,012
Year Three	899,289	416,106
Year Four	353,241	388,651
Year Five	318,570	444,471
Prior Years	2,204,900	2,300,036
Revolving Line of Credit	0	0
Total Amortized Cost	6,416,358	6,180,495
One- to Four-Family Segment [Member] | Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	4,038,544	3,979,536
One- to Four-Family Segment [Member] | Originated [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	563,460	958,080
Year Two	930,019	705,561
Year Three	624,274	326,156
Year Four	281,342	250,846
Year Five	212,037	281,104
Prior Years	1,406,444	1,434,455
Revolving Line of Credit	0	0
Total Amortized Cost	4,017,576	3,956,202
One- to Four-Family Segment [Member] | Originated [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	47	402
Year Two	457	443
Year Three	1,111	501
Year Four	518	678
Year Five	428	237
Prior Years	7,641	7,805
Revolving Line of Credit	0	0
Total Amortized Cost	10,202	10,066
One- to Four-Family Segment [Member] | Originated [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	158	0
Year Two	0	966
Year Three	278	867
Year Four	1,106	51
Year Five	256	192
Prior Years	8,968	11,192
Revolving Line of Credit	0	0
Total Amortized Cost	10,766	13,268
One- to Four-Family Segment [Member] | Correspondent Purchased [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	2,229,337	2,026,592
One- to Four-Family Segment [Member] | Correspondent Purchased [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	494,854	630,977
Year Two	651,363	334,042
Year Three	273,626	88,057
Year Four	69,752	136,572
Year Five	104,150	162,938
Prior Years	627,390	664,530
Revolving Line of Credit	0	0
Total Amortized Cost	2,221,135	2,017,116
One- to Four-Family Segment [Member] | Correspondent Purchased [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	760
Year Two	0	0
Year Three	0	356
Year Four	355	0
Year Five	1,186	0
Prior Years	1,197	3,160
Revolving Line of Credit	0	0
Total Amortized Cost	2,738	4,276
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	169
Year Four	168	504
Year Five	513	0
Prior Years	4,783	4,527
Revolving Line of Credit	0	0
Total Amortized Cost	5,464	5,200
One- to Four-Family Segment [Member] | Bulk Purchased [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	148,477	174,367
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	144,840	169,519
Revolving Line of Credit	0	0
Total Amortized Cost	144,840	169,519
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
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	3,637	4,848
Revolving Line of Credit	0	0
Total Amortized Cost	3,637	4,848
Commercial Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	406,237	356,142
Year Two	238,454	160,039
Year Three	118,069	102,185
Year Four	90,889	64,182
Year Five	42,553	40,165
Prior Years	47,053	85,589
Revolving Line of Credit	19,901	17,705
Total Amortized Cost	963,156	826,007
Commercial Segment [Member] | Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	883,166	759,629
Commercial Segment [Member] | Commercial Real Estate [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	366,794	272,329
Year Two	221,001	149,244
Year Three	111,689	94,972
Year Four	86,456	61,214
Year Five	41,322	38,962
Prior Years	46,383	35,591
Revolving Line of Credit	7,436	5,231
Total Amortized Cost	881,081	657,543
Commercial Segment [Member] | Commercial Real Estate [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	565	50,352
Year Two	0	0
Year Three	0	0
Year Four	0	0
Year Five	0	0
Prior Years	0	49,369
Revolving Line of Credit	0	0
Total Amortized Cost	565	99,721
Commercial Segment [Member] | Commercial Real Estate [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	436	810
Year Two	0	627
Year Three	594	225
Year Four	221	669
Year Five	239	0
Prior Years	30	34
Revolving Line of Credit	0	0
Total Amortized Cost	1,520	2,365
Commercial Segment [Member] | Commercial and Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	79,990	66,378
Commercial Segment [Member] | Commercial and Industrial [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	38,442	32,651
Year Two	17,453	10,168
Year Three	5,708	6,988
Year Four	4,212	2,213
Year Five	919	1,155
Prior Years	630	595
Revolving Line of Credit	11,413	11,709
Total Amortized Cost	78,777	65,479
Commercial Segment [Member] | Commercial and Industrial [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
Total Amortized Cost	0	0
Commercial Segment [Member] | Commercial and Industrial [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	0
Year Two	0	0
Year Three	78	0
Year Four	0	86
Year Five	73	48
Prior Years	10	0
Revolving Line of Credit	1,052	765
Total Amortized Cost	1,213	899
Consumer Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	10,655	6,786
Year Two	4,418	3,912
Year Three	2,336	2,561
Year Four	1,408	2,520
Year Five	1,643	1,004
Prior Years	2,224	2,587
Revolving Line of Credit	78,381	75,093
Total Amortized Cost	101,065	94,463
Consumer Segment [Member] | Home Equity [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	92,401	86,385
Consumer Segment [Member] | Home Equity [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	6,447	3,295
Year Two	2,375	2,218
Year Three	1,486	1,428
Year Four	982	1,563
Year Five	992	536
Prior Years	2,020	2,473
Revolving Line of Credit	77,448	74,036
Total Amortized Cost	91,750	85,549
Consumer Segment [Member] | Home Equity [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	0
Year Two	66	0
Year Three	0	37
Year Four	0	12
Year Five	0	0
Prior Years	0	0
Revolving Line of Credit	233	82
Total Amortized Cost	299	131
Consumer Segment [Member] | Home Equity [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0	0
Year Two	0	60
Year Three	0	0
Year Four	18	0
Year Five	0	0
Prior Years	3	9
Revolving Line of Credit	331	636
Total Amortized Cost	352	705
Consumer Segment [Member] | Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Amortized Cost	8,664	8,078
Consumer Segment [Member] | Other [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	4,207	3,491
Year Two	1,977	1,631
Year Three	843	1,086
Year Four	408	944
Year Five	651	465
Prior Years	201	105
Revolving Line of Credit	369	339
Total Amortized Cost	8,656	8,061
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	7	4
Year Four	0	0
Year Five	0	0
Prior Years	0	0
Revolving Line of Credit	0	0
Total Amortized Cost	7	4
Consumer Segment [Member] | Other [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	1	0
Year Two	0	3
Year Three	0	6
Year Four	0	1
Year Five	0	3
Prior Years	0	0
Revolving Line of Credit	0	0
Total Amortized Cost	$ 1	$ 13