Receivable and Allowance for Credit Losses - Credit Quality Indicators (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Total Writeoff	$ 3,494	$ 638	$ 3,564
Real estate loans | One-to-four family
Financing Receivable, Credit Quality Indicator [Line Items]
Total Writeoff	585	382	773
Real estate loans | Multifamily
Financing Receivable, Credit Quality Indicator [Line Items]
Total Writeoff	0	0	296
Real estate loans | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total Writeoff	150	0	407
Real estate loans | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Total Writeoff	0	0	0
Commercial business loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total Writeoff	2,618	190	1,773
Consumer loans | Home equity loans and advances
Financing Receivable, Credit Quality Indicator [Line Items]
Total Writeoff	26	33	308
Consumer loans | Other consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total Writeoff	115	33	$ 7
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	648,608	1,836,787
2023/2022, Writeoff	0	10
2022/2021	1,882,747	1,697,890
2022/2021, Writeoff	269	18
2021/2020	1,639,402	710,769
2021/2020, Writeoff	280	50
2020/2019	649,900	694,400
2020/2019, Writeoff	34	143
2019/2018	632,951	451,367
2019/2018, Writeoff	2,342	151
Prior	1,981,490	1,831,970
Prior, Writeoff	569	266
Revolving Loans	325,009	400,894
Revolving Loans, Writeoff	0	0
Revolving Loans to Term Loans	64,558	457
Revolving Loans to Term Loans, Writeoff	0	0
Total	7,824,665	7,624,534
Total Writeoff	3,494	638
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | One-to-four family
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	156,279	829,363
2023/2022, Writeoff	0	0
2022/2021	787,911	836,996
2022/2021, Writeoff	208	0
2021/2020	793,843	294,721
2021/2020, Writeoff	197	50
2020/2019	272,498	177,795
2020/2019, Writeoff	0	0
2019/2018	165,966	125,377
2019/2018, Writeoff	29	122
Prior	616,336	595,932
Prior, Writeoff	151	210
Revolving Loans	0	0
Revolving Loans, Writeoff	0	0
Revolving Loans to Term Loans	0	0
Revolving Loans to Term Loans, Writeoff	0	0
Total	2,792,833	2,860,184
Total Writeoff	585	382
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | One-to-four family | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	156,279	829,363
2022/2021	786,735	836,355
2021/2020	793,074	294,721
2020/2019	272,215	177,114
2019/2018	165,337	125,057
Prior	614,351	595,097
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	2,787,991	2,857,707
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | One-to-four family | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0	0
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
Prior	0	0
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	0	0
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | One-to-four family | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0	0
2022/2021	1,176	641
2021/2020	769	0
2020/2019	283	681
2019/2018	629	320
Prior	1,985	835
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	4,842	2,477
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Multifamily
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	111,612	315,157
2023/2022, Writeoff	0	0
2022/2021	317,277	309,611
2022/2021, Writeoff	0	0
2021/2020	359,983	167,955
2021/2020, Writeoff	0	0
2020/2019	157,294	205,608
2020/2019, Writeoff	0	0
2019/2018	202,923	38,849
2019/2018, Writeoff	0	0
Prior	260,098	202,027
Prior, Writeoff	0	0
Revolving Loans	0	0
Revolving Loans, Writeoff	0	0
Revolving Loans to Term Loans	0	0
Revolving Loans to Term Loans, Writeoff	0	0
Total	1,409,187	1,239,207
Total Writeoff	0	0
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Multifamily | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	111,612	315,157
2022/2021	317,277	309,611
2021/2020	359,983	167,955
2020/2019	157,294	205,608
2019/2018	202,923	38,849
Prior	255,578	197,489
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	1,404,667	1,234,669
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Multifamily | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0	0
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
Prior	4,520	4,538
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	4,520	4,538
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Multifamily | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0	0
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
Prior	0	0
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	0	0
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	191,030	448,313
2023/2022, Writeoff	0	0
2022/2021	427,801	393,167
2022/2021, Writeoff	0	0
2021/2020	372,948	173,254
2021/2020, Writeoff	0	0
2020/2019	176,504	262,767
2020/2019, Writeoff	0	0
2019/2018	237,134	247,366
2019/2018, Writeoff	64	0
Prior	971,660	888,527
Prior, Writeoff	86	0
Revolving Loans	0	0
Revolving Loans, Writeoff	0	0
Revolving Loans to Term Loans	0	0
Revolving Loans to Term Loans, Writeoff	0	0
Total	2,377,077	2,413,394
Total Writeoff	150	0
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Commercial real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	191,030	448,313
2022/2021	422,058	392,689
2021/2020	371,578	170,125
2020/2019	174,705	260,268
2019/2018	236,263	231,868
Prior	930,740	852,104
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	2,326,374	2,355,367
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Commercial real estate | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0	0
2022/2021	0	478
2021/2020	465	1,843
2020/2019	0	892
2019/2018	871	15,498
Prior	24,405	20,939
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	25,741	39,650
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Commercial real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0	0
2022/2021	5,743	0
2021/2020	905	1,286
2020/2019	1,799	1,607
2019/2018	0	0
Prior	16,515	15,484
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	24,962	18,377
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	99,634	159,751
2023/2022, Writeoff	0	0
2022/2021	270,397	104,339
2022/2021, Writeoff	0	0
2021/2020	65,374	28,058
2021/2020, Writeoff	0	0
2020/2019	4,933	14,216
2020/2019, Writeoff	0	0
2019/2018	439	870
2019/2018, Writeoff	0	0
Prior	2,317	29,319
Prior, Writeoff	0	0
Revolving Loans	0	0
Revolving Loans, Writeoff	0	0
Revolving Loans to Term Loans	0	0
Revolving Loans to Term Loans, Writeoff	0	0
Total	443,094	336,553
Total Writeoff	0	0
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Construction | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	99,634	159,751
2022/2021	270,397	104,339
2021/2020	65,374	28,058
2020/2019	4,933	14,216
2019/2018	439	870
Prior	2,317	29,319
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	443,094	336,553
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Construction | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0	0
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
Prior	0	0
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	0	0
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Construction | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0	0
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
Prior	0	0
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	0	0
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Commercial business loans
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	67,656	58,631
2023/2022, Writeoff	0	0
2022/2021	58,497	33,214
2022/2021, Writeoff	0	0
2021/2020	29,077	32,911
2021/2020, Writeoff	31	0
2020/2019	27,297	21,842
2020/2019, Writeoff	34	143
2019/2018	16,594	27,749
2019/2018, Writeoff	2,249	29
Prior	46,493	27,630
Prior, Writeoff	304	18
Revolving Loans	287,427	295,492
Revolving Loans, Writeoff	0	0
Revolving Loans to Term Loans	0	0
Revolving Loans to Term Loans, Writeoff	0	0
Total	533,041	497,469
Total Writeoff	2,618	190
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Commercial business loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	67,529	58,631
2022/2021	58,118	32,880
2021/2020	28,989	32,788
2020/2019	27,194	20,705
2019/2018	15,499	24,634
Prior	38,954	27,277
Revolving Loans	272,698	280,857
Revolving Loans to Term Loans	0	0
Total	508,981	477,772
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Commercial business loans | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	127	0
2022/2021	303	110
2021/2020	0	63
2020/2019	97	1,137
2019/2018	14	1,030
Prior	1,389	38
Revolving Loans	4,587	10,761
Revolving Loans to Term Loans	0	0
Total	6,517	13,139
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Commercial business loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0	0
2022/2021	76	224
2021/2020	88	60
2020/2019	6	0
2019/2018	1,081	2,085
Prior	6,150	315
Revolving Loans	10,142	3,874
Revolving Loans to Term Loans	0	0
Total	17,543	6,558
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Consumer loans | Home equity loans and advances
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	20,198	22,903
2023/2022, Writeoff	0	0
2022/2021	20,713	20,476
2022/2021, Writeoff	0	0
2021/2020	18,139	13,770
2021/2020, Writeoff	0	0
2020/2019	11,368	12,070
2020/2019, Writeoff	0	0
2019/2018	9,877	11,126
2019/2018, Writeoff	0	0
Prior	84,518	88,439
Prior, Writeoff	26	33
Revolving Loans	37,261	105,061
Revolving Loans, Writeoff	0	0
Revolving Loans to Term Loans	64,558	457
Revolving Loans to Term Loans, Writeoff	0	0
Total	266,632	274,302
Total Writeoff	26	33
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Consumer loans | Home equity loans and advances | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	20,198	22,903
2022/2021	20,713	20,476
2021/2020	18,139	13,770
2020/2019	11,368	12,070
2019/2018	9,877	11,126
Prior	84,261	88,251
Revolving Loans	37,261	105,005
Revolving Loans to Term Loans	64,558	457
Total	266,375	274,058
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Consumer loans | Home equity loans and advances | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0	0
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
Prior	0	0
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	0	0
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Consumer loans | Home equity loans and advances | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0	0
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
Prior	257	188
Revolving Loans	0	56
Revolving Loans to Term Loans	0	0
Total	257	244
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Consumer loans | Other consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	2,199	2,669
2023/2022, Writeoff	0	10
2022/2021	151	87
2022/2021, Writeoff	61	18
2021/2020	38	100
2021/2020, Writeoff	52	0
2020/2019	6	102
2020/2019, Writeoff	0	0
2019/2018	18	30
2019/2018, Writeoff	0	0
Prior	68	96
Prior, Writeoff	2	5
Revolving Loans	321	341
Revolving Loans, Writeoff	0	0
Revolving Loans to Term Loans	0	0
Revolving Loans to Term Loans, Writeoff	0	0
Total	2,801	3,425
Total Writeoff	115	33
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Consumer loans | Other consumer loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	2,199	2,669
2022/2021	151	87
2021/2020	38	100
2020/2019	6	102
2019/2018	18	30
Prior	68	96
Revolving Loans	321	341
Revolving Loans to Term Loans	0	0
Total	2,801	3,425
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Consumer loans | Other consumer loans | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0	0
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
Prior	0	0
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	0	0
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Consumer loans | Other consumer loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0	0
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
Prior	0	0
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	$ 0	$ 0