Loans Receivable And Allowance For Credit Losses (Allowance For Credit Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				$ 31,527
Beginning Balance	$ 17,535	$ 26,125	$ 19,823
Charge-offs	(5)	(138)	(20)	(670)
Recoveries	19	68	65	136
Provision for credit losses	(2,237)	(2,658)	(4,556)	(2,835)
Ending Balance	15,312	23,397	15,312	23,397
Adoption of CECL [Member] | Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				(4,761)
Balance at October 1, 2020 [Member] | Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				26,766
One- to Four-Family Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				9,243
Beginning Balance	3,989	4,148	3,978
Charge-offs	0	(131)	(4)	(145)
Recoveries	2	57	11	91
Provision for credit losses	88	(86)	94	(818)
Ending Balance	4,079	3,988	4,079	3,988
One- to Four-Family Segment [Member] | Adoption of CECL [Member] | Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				(4,383)
One- to Four-Family Segment [Member] | Balance at October 1, 2020 [Member] | Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				4,860
One- to Four-Family Segment [Member] | Originated [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				6,085
Beginning Balance	1,639	1,538	1,612
Charge-offs	0	(110)	(4)	(124)
Recoveries	2	57	11	91
Provision for credit losses	68	51	90	(64)
Ending Balance	1,709	1,536	1,709	1,536
One- to Four-Family Segment [Member] | Originated [Member] | Adoption of CECL [Member] | Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				(4,452)
One- to Four-Family Segment [Member] | Originated [Member] | Balance at October 1, 2020 [Member] | Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				1,633
One- to Four-Family Segment [Member] | Correspondent Purchased [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				2,691
Beginning Balance	2,082	1,758	2,062
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision for credit losses	47	(53)	67	(619)
Ending Balance	2,129	1,705	2,129	1,705
One- to Four-Family Segment [Member] | Correspondent Purchased [Member] | Adoption of CECL [Member] | Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				(367)
One- to Four-Family Segment [Member] | Correspondent Purchased [Member] | Balance at October 1, 2020 [Member] | Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				2,324
One- to Four-Family Segment [Member] | Bulk Purchased [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				467
Beginning Balance	268	852	304
Charge-offs	0	(21)	0	(21)
Recoveries	0	0	0	0
Provision for credit losses	(27)	(84)	(63)	(135)
Ending Balance	241	747	241	747
One- to Four-Family Segment [Member] | Bulk Purchased [Member] | Adoption of CECL [Member] | Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				436
One- to Four-Family Segment [Member] | Bulk Purchased [Member] | Balance at October 1, 2020 [Member] | Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				903
Commercial Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				21,800
Beginning Balance	13,353	21,707	15,652
Charge-offs	0	0	(10)	(515)
Recoveries	13	8	49	20
Provision for credit losses	(2,335)	(2,558)	(4,660)	(1,955)
Ending Balance	11,031	19,157	11,031	19,157
Commercial Segment [Member] | Adoption of CECL [Member] | Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				(193)
Commercial Segment [Member] | Balance at October 1, 2020 [Member] | Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				21,607
Consumer Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				484
Beginning Balance	193	270	193
Charge-offs	(5)	(7)	(6)	(10)
Recoveries	4	3	5	25
Provision for credit losses	10	(14)	10	(62)
Ending Balance	$ 202	$ 252	$ 202	252
Consumer Segment [Member] | Adoption of CECL [Member] | Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				(185)
Consumer Segment [Member] | Balance at October 1, 2020 [Member] | Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance				$ 299