Loans Receivable and Allowance for Credit Losses - Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 57,062	$ 53,456	$ 55,096	$ 52,803	$ 52,803
Provision for (reversal of) credit losses	4,103	2,379	11,575	3,632
Recoveries	102	674	521	909
Charge-offs	(2,772)	(2,396)	(8,697)	(3,231)
Balance at end of period	58,495	54,113	58,495	54,113	55,096
Commercial real estate | One-to-four family
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	14,888	11,026	13,017	11,802	11,802
Provision for (reversal of) credit losses	(2,055)	1,063	(184)	421
Recoveries	8	0	10	0
Charge-offs	0	(218)	(2)	(352)
Balance at end of period	12,841	11,871	12,841	11,871	13,017
Commercial real estate | Multifamily
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	8,391	9,392	8,742	7,877	7,877
Provision for (reversal of) credit losses	124	117	(227)	1,632
Recoveries	0	0	0	0
Charge-offs	0	0	0	0
Balance at end of period	8,515	9,509	8,515	9,509	8,742
Commercial real estate | Commercial real estate
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	15,080	16,212	15,757	18,111	18,111
Provision for (reversal of) credit losses	440	(454)	(117)	(2,203)
Recoveries	36	0	36	0
Charge-offs	0	0	(120)	(150)
Balance at end of period	15,556	15,758	15,556	15,758	15,757
Commercial real estate | Construction
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	8,549	6,935	7,758	6,425	6,425
Provision for (reversal of) credit losses	(1,474)	10	(685)	520
Recoveries	1	0	3	0
Charge-offs	0	0	0	0
Balance at end of period	7,076	6,945	7,076	6,945	7,758
Commercial business loans | Commercial Business
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	7,494	7,690	7,923	6,897	6,897
Provision for (reversal of) credit losses	8,267	1,688	13,076	2,725
Recoveries	50	624	455	830
Charge-offs	(2,696)	(2,168)	(8,339)	(2,618)
Balance at end of period	13,115	7,834	13,115	7,834	7,923
Consumer loans | Home equity loans and advances
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	2,654	2,193	1,892	1,681	1,681
Provision for (reversal of) credit losses	(1,275)	(53)	(522)	460
Recoveries	5	49	14	73
Charge-offs	0	0	0	(25)
Balance at end of period	1,384	2,189	1,384	2,189	1,892
Consumer loans | Other consumer loans
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	6	8	7	10	10
Provision for (reversal of) credit losses	76	8	234	77
Recoveries	2	1	3	6
Charge-offs	(76)	(10)	(236)	(86)
Balance at end of period	$ 8	$ 7	$ 8	$ 7	$ 7