Loans Receivable and Allowance for Credit Losses - Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 67,201	$ 59,958	$ 59,958
Provision for (reversal of) credit losses	956	2,933
Recoveries	683	134
Charge-offs	(79)	(991)
Balance at end of period	68,761	62,034	67,201
Real estate loans \| One-to-four family
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	13,283	13,173	13,173
Provision for (reversal of) credit losses	(55)	(304)
Recoveries	1	1
Charge-offs	0	0
Balance at end of period	13,229	12,870	13,283
Real estate loans \| Multifamily
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	10,647	9,542	9,542
Provision for (reversal of) credit losses	(519)	421
Recoveries	0	0
Charge-offs	0	0
Balance at end of period	10,128	9,963	10,647
Real estate loans \| Commercial real estate
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	18,592	15,969	15,969
Provision for (reversal of) credit losses	338	1,519
Recoveries	0	1
Charge-offs	0	(77)
Balance at end of period	18,930	17,412	18,592
Real estate loans \| Construction
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	6,617	6,703	6,703
Provision for (reversal of) credit losses	1,351	(388)
Recoveries	0	1
Charge-offs	0	(53)
Balance at end of period	7,968	6,263	6,617
Commercial business loans \| Commercial business
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	16,767	13,112	13,112
Provision for (reversal of) credit losses	(211)	1,873
Recoveries	668	97
Charge-offs	0	(825)
Balance at end of period	17,224	14,257	16,767
Home equity loans and advances \| Home equity loans and advances
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	1,289	1,452	1,452
Provision for (reversal of) credit losses	(18)	(221)
Recoveries	5	33
Charge-offs	0	0
Balance at end of period	1,276	1,264	1,289
Home equity loans and advances \| Other consumer loans
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	6	7	7
Provision for (reversal of) credit losses	70	33
Recoveries	9	1
Charge-offs	(79)	(36)
Balance at end of period	$ 6	$ 5	$ 6

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

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

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- Definition

Amount, excluding accrued interest, of increase in allowance for credit loss on financing receivable from recovery. 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 13
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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+ References

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

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- Definition

Amount, excluding accrued interest, of credit loss expense (reversal of expense) on financing receivable. 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 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476148/220-40-50-22

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