LOANS RECEIVABLE - Loans Based on Credit Quality Indicators (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2025	Sep. 30, 2024
Gross Charge-offs
Total Loans	$ 13,170	$ 3,625
Commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
2025	883,049	492,643
2024	559,800	1,062,522
2023	1,063,002	3,617,204
2022	3,228,956	2,540,773
2021	2,168,469	1,201,276
Prior to 2021	2,525,463	1,857,904
Revolving Loans	1,379,579	1,374,384
Revolving to Term Loans	43,339	58,714
Total Loans	11,851,657	12,205,420
Gross Charge-offs
2025	381	175
2024	307	42
2023	0	10
2022	163	15
2021	271	0
Prior to 2021	10,212	359
Revolving Loans	0	2,331
Revolving to Term Loans	164	31
Total Loans	11,498	2,963
Commercial loans \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2025	845,225	490,419
2024	554,579	1,034,082
2023	1,008,590	3,551,477
2022	3,039,241	2,488,588
2021	2,031,404	1,144,343
Prior to 2021	2,239,804	1,688,884
Revolving Loans	1,237,513	1,267,493
Revolving to Term Loans	38,148	58,710
Total Loans	10,994,504	11,723,996
Commercial loans \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0	0
2024	1,975	0
2023	8,225	1,698
2022	93,081	28,092
2021	35,614	11,254
Prior to 2021	98,484	14,851
Revolving Loans	10,451	21,264
Revolving to Term Loans	0	0
Total Loans	247,830	77,159
Commercial loans \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2025	37,824	2,224
2024	3,246	28,440
2023	46,177	64,029
2022	96,634	24,093
2021	101,451	45,679
Prior to 2021	182,041	154,169
Revolving Loans	131,615	85,627
Revolving to Term Loans	5,180	4
Total Loans	604,168	404,265
Commercial loans \| Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	0
2022	0
2021	0
Prior to 2021	5,131
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	5,131
Commercial loans \| Loss
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	10
2022	0
2021	0
Prior to 2021	3
Revolving Loans	0
Revolving to Term Loans	11
Total Loans	24
Commercial loans \| Multi-family
Financing Receivable, Credit Quality Indicator [Line Items]
2025	54,113	62,038
2024	91,285	198,790
2023	448,792	1,660,724
2022	1,616,985	1,211,510
2021	1,180,536	586,668
Prior to 2021	1,217,560	763,090
Revolving Loans	22,050	56,627
Revolving to Term Loans	0	16,753
Total Loans	4,631,321	4,556,200
Gross Charge-offs
2025	182
2024	0
2023	0
2022	0
2021	271
Prior to 2021	102
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	555	0
Commercial loans \| Multi-family \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2025	51,779	62,038
2024	91,285	198,790
2023	431,401	1,645,460
2022	1,521,149	1,203,005
2021	1,154,189	577,037
Prior to 2021	1,066,496	716,573
Revolving Loans	21,048	56,627
Revolving to Term Loans	0	16,753
Total Loans	4,337,347	4,476,283
Commercial loans \| Multi-family \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0	0
2024	0	0
2023	8,225	1,698
2022	44,350	2,655
2021	13,686	2,572
Prior to 2021	70,556	5,452
Revolving Loans	0	0
Revolving to Term Loans	0	0
Total Loans	136,817	12,377
Commercial loans \| Multi-family \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2025	2,334	0
2024	0	0
2023	9,166	13,566
2022	51,486	5,850
2021	12,661	7,059
Prior to 2021	78,158	41,065
Revolving Loans	1,002	0
Revolving to Term Loans	0	0
Total Loans	154,807	67,540
Commercial loans \| Multi-family \| Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	0
2022	0
2021	0
Prior to 2021	2,350
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	2,350
Commercial loans \| Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2025	311,687	216,520
2024	226,269	252,923
2023	246,616	1,094,886
2022	1,040,282	748,076
2021	655,827	509,314
Prior to 2021	1,073,483	875,187
Revolving Loans	33,688	35,249
Revolving to Term Loans	1,098	0
Total Loans	3,588,950	3,732,155
Gross Charge-offs
2025	0	0
2024	0	0
2023	0	0
2022	163	0
2021	0	0
Prior to 2021	9,489	203
Revolving Loans	0	0
Revolving to Term Loans	0	0
Total Loans	9,652	203
Commercial loans \| Commercial real estate \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2025	311,687	216,520
2024	226,269	252,923
2023	231,132	1,086,200
2022	997,347	723,600
2021	550,234	475,313
Prior to 2021	987,607	797,877
Revolving Loans	33,688	35,249
Revolving to Term Loans	1,098	0
Total Loans	3,339,062	3,587,682
Commercial loans \| Commercial real estate \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0	0
2024	0	0
2023	0	0
2022	27,900	22,216
2021	21,928	8,682
Prior to 2021	11,752	9,399
Revolving Loans	0	0
Revolving to Term Loans	0	0
Total Loans	61,580	40,297
Commercial loans \| Commercial real estate \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0	0
2024	0	0
2023	15,484	8,686
2022	15,035	2,260
2021	83,665	25,319
Prior to 2021	71,343	67,911
Revolving Loans	0	0
Revolving to Term Loans	0	0
Total Loans	185,527	104,176
Commercial loans \| Commercial real estate \| Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	0
2022	0
2021	0
Prior to 2021	2,781
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	2,781
Commercial loans \| Commercial & industrial
Financing Receivable, Credit Quality Indicator [Line Items]
2025	299,127	44,374
2024	51,834	167,877
2023	135,361	266,932
2022	188,651	284,432
2021	228,768	102,446
Prior to 2021	232,785	201,536
Revolving Loans	1,207,596	1,223,174
Revolving to Term Loans	42,241	41,961
Total Loans	2,386,363	2,332,732
Gross Charge-offs
2025	199	175
2024	307	42
2023	0	10
2022	0	15
2021	0	0
Prior to 2021	621	7
Revolving Loans	0	2,331
Revolving to Term Loans	164	31
Total Loans	1,291	2,611
Commercial loans \| Commercial & industrial \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2025	263,637	42,232
2024	46,817	148,059
2023	113,824	231,215
2022	147,522	282,148
2021	227,043	89,219
Prior to 2021	184,325	156,666
Revolving Loans	1,066,532	1,116,283
Revolving to Term Loans	37,050	41,957
Total Loans	2,086,750	2,107,779
Commercial loans \| Commercial & industrial \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0	0
2024	1,975	0
2023	0	0
2022	16,396	0
2021	0	0
Prior to 2021	16,176	0
Revolving Loans	10,451	21,264
Revolving to Term Loans	0	0
Total Loans	44,998	21,264
Commercial loans \| Commercial & industrial \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2025	35,490	2,142
2024	3,042	19,818
2023	21,527	35,717
2022	24,733	2,284
2021	1,725	13,227
Prior to 2021	32,281	44,870
Revolving Loans	130,613	85,627
Revolving to Term Loans	5,180	4
Total Loans	254,591	203,689
Commercial loans \| Commercial & industrial \| Loss
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	10
2022	0
2021	0
Prior to 2021	3
Revolving Loans	0
Revolving to Term Loans	11
Total Loans	24
Commercial loans \| Construction
Financing Receivable, Credit Quality Indicator [Line Items]
2025	169,743	146,236
2024	171,762	429,956
2023	221,207	538,370
2022	355,866	250,120
2021	70,278	0
Prior to 2021	0	0
Revolving Loans	116,245	59,334
Revolving to Term Loans	0	0
Total Loans	1,105,101	1,424,016
Gross Charge-offs
Total Loans	0	0
Commercial loans \| Construction \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2025	169,743	146,154
2024	171,558	421,334
2023	221,207	532,310
2022	346,051	233,200
2021	66,878	0
Prior to 2021	0	0
Revolving Loans	116,245	59,334
Revolving to Term Loans	0	0
Total Loans	1,091,682	1,392,332
Commercial loans \| Construction \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0	0
2024	0	0
2023	0	0
2022	4,435	3,221
2021	0	0
Prior to 2021	0	0
Revolving Loans	0	0
Revolving to Term Loans	0	0
Total Loans	4,435	3,221
Commercial loans \| Construction \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0	82
2024	204	8,622
2023	0	6,060
2022	5,380	13,699
2021	3,400	0
Prior to 2021	0	0
Revolving Loans	0	0
Revolving to Term Loans	0	0
Total Loans	8,984	28,463
Commercial loans \| Land - acquisition & development
Financing Receivable, Credit Quality Indicator [Line Items]
2025	48,379	23,475
2024	18,650	12,976
2023	11,026	56,292
2022	27,172	46,635
2021	33,060	2,848
Prior to 2021	1,635	18,091
Revolving Loans	0	0
Revolving to Term Loans	0	0
Total Loans	139,922	160,317
Gross Charge-offs
2025		0
2024		0
2023		0
2022		0
2021		0
Prior to 2021		149
Revolving Loans		0
Revolving to Term Loans		0
Total Loans	0	149
Commercial loans \| Land - acquisition & development \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2025	48,379	23,475
2024	18,650	12,976
2023	11,026	56,292
2022	27,172	46,635
2021	33,060	2,774
Prior to 2021	1,376	17,768
Revolving Loans	0	0
Revolving to Term Loans	0	0
Total Loans	139,663	159,920
Commercial loans \| Land - acquisition & development \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0	0
2024	0	0
2023	0	0
2022	0	0
2021	0	74
Prior to 2021	259	323
Revolving Loans	0	0
Revolving to Term Loans	0	0
Total Loans	259	397
Consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
2025	244,586	460,352
2024	404,098	893,513
2023	804,587	2,334,575
2022	2,172,927	2,097,678
2021	1,952,399	817,561
Prior to 2021	2,560,048	2,009,369
Revolving Loans	295,685	300,523
Revolving to Term Loans	2,351	1,116
Total Loans	8,436,681	8,914,687
Gross Charge-offs
2025	0	0
2024	2	0
2023	0	13
2022	0	0
2021	0	0
Prior to 2021	400	270
Revolving Loans	1,252	379
Revolving to Term Loans	18	0
Total Loans	1,672	662
Consumer loans \| Current
Financing Receivable, Credit Quality Indicator [Line Items]
2025	244,184	460,352
2024	401,775	889,456
2023	800,998	2,329,898
2022	2,166,648	2,095,140
2021	1,940,345	814,809
Prior to 2021	2,537,093	1,992,035
Revolving Loans	293,676	298,047
Revolving to Term Loans	2,247	1,116
Total Loans	8,386,966	8,880,853
Consumer loans \| 30 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
2025	402	0
2024	949	0
2023	1,751	375
2022	1,116	0
2021	7,301	1,063
Prior to 2021	5,514	2,797
Revolving Loans	1,282	1,390
Revolving to Term Loans	104	0
Total Loans	18,419	5,625
Consumer loans \| 60 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0	0
2024	376	3,237
2023	1,025	0
2022	692	1,199
2021	339	662
Prior to 2021	4,037	2,834
Revolving Loans	253	329
Revolving to Term Loans	0	0
Total Loans	6,722	8,261
Consumer loans \| 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0	0
2024	998	820
2023	813	4,302
2022	4,471	1,339
2021	4,414	1,027
Prior to 2021	13,404	11,703
Revolving Loans	474	757
Revolving to Term Loans	0	0
Total Loans	24,574	19,948
Consumer loans \| Construction
Financing Receivable, Credit Quality Indicator [Line Items]
2025	34,932	54,649
2024	33,380	108,941
2023	5,256	17,930
2022	4,675	537
2021	0	0
Prior to 2021	0	358
Revolving Loans	0	0
Revolving to Term Loans	0	0
Total Loans	78,243	182,415
Gross Charge-offs
Total Loans	0	0
Consumer loans \| Construction \| Current
Financing Receivable, Credit Quality Indicator [Line Items]
2025	34,932	54,649
2024	33,380	108,941
2023	5,256	17,082
2022	3,915	537
2021	0	0
Prior to 2021	0	358
Revolving Loans	0	0
Revolving to Term Loans	0	0
Total Loans	77,483	181,567
Consumer loans \| Construction \| 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0	0
2024	0	0
2023	0	848
2022	760	0
2021	0	0
Prior to 2021	0	0
Revolving Loans	0	0
Revolving to Term Loans	0	0
Total Loans	760	848
Consumer loans \| Single-family residential
Financing Receivable, Credit Quality Indicator [Line Items]
2025	203,321	384,516
2024	356,002	769,730
2023	790,163	2,289,825
2022	2,148,708	2,063,897
2021	1,924,325	800,338
Prior to 2021	2,514,412	1,971,994
Revolving Loans	0	0
Revolving to Term Loans	0	0
Total Loans	7,936,931	8,280,300
Gross Charge-offs
2025	0	0
2024	0	0
2023	0	13
2022	0	0
2021	0	0
Prior to 2021	338	131
Revolving Loans	0	0
Revolving to Term Loans	0	0
Total Loans	338	144
Consumer loans \| Single-family residential \| Current
Financing Receivable, Credit Quality Indicator [Line Items]
2025	202,919	384,516
2024	353,679	765,673
2023	786,634	2,285,996
2022	2,143,244	2,061,359
2021	1,912,465	797,586
Prior to 2021	2,491,902	1,955,459
Revolving Loans	0	0
Revolving to Term Loans	0	0
Total Loans	7,890,843	8,250,589
Consumer loans \| Single-family residential \| 30 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
2025	402	0
2024	949	0
2023	1,751	375

Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from writeoff. Excludes net investment in lease.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoffByOriginationYearAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 948
-SubTopic 310
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477011/948-310-45-1

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost excluding accrued interest, of financing receivable originated more than five years prior to current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated more than five years before current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amortized cost excluding accrued interest, of financing receivable that can be withdrawn, repaid, and redrawn.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestRevolving
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost excluding accrued interest, of revolving financing receivable converted to term loan.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6A

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoan
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, excluding accrued interest, of writeoff of revolving financing receivable converted to term loan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6A

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoanWriteoff
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable that can be withdrawn, repaid, and redrawn.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingWriteoff
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amortized cost excluding accrued interest, of financing receivable originated four years prior to current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated four years before current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amortized cost excluding accrued interest, of financing receivable originated three years prior to current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated three years before current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amortized cost excluding accrued interest, of financing receivable originated in current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated in current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amortized cost excluding accrued interest, of financing receivable originated two years prior to current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated two years before current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amortized cost excluding accrued interest of financing receivable originated in fiscal year prior to current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated in fiscal year before current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (d)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (d)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (d)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (d)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 8: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-15

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-5

Reference 11: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-15

Reference 12: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (c)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 13: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 14: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (e)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 15: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (e)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 16: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (b)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 17: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (b)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 18: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 19: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-15

Reference 20: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-15

Reference 21: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-15

Reference 22: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 29
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-29

Reference 23: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_PassMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_SpecialMentionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_SubstandardMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_DoubtfulMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=wfsl_LossMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=srt_MultifamilyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=wfsl_CommercialandIndustrialMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConstructionLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=wfsl_LandAcquisitionAndDevelopmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancialAssetNotPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivables1To29DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivables30To59DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=srt_SingleFamilyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=wfsl_LandConsumerLotLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivables60To89DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_HomeEquityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConsumerLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	wfsl_NettingAxis=wfsl_NettingAdjustmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: