Loans Receivable and Allowance for Credit Losses - Credit Quality Indicators (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 7,641,593	$ 6,335,722
Real estate loans | One-to-four family
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,862,342	2,092,748
Real estate loans | Multifamily
Financing Receivable, Credit Quality Indicator [Line Items]
Total	1,239,207	1,041,108
Real estate loans | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,426,510	2,175,662
Real estate loans | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Total	337,593	295,047
Commercial business loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	497,965	453,166
Consumer loans | Home equity loans and advances
Financing Receivable, Credit Quality Indicator [Line Items]
Total	274,551	276,563
Consumer loans | Other consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	3,425	1,428
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Credit Quality Indicator [Line Items]
2022	1,836,787	1,702,481
2021	1,697,890	771,407
2020	710,769	789,875
2019	694,400	533,879
2018	451,367	555,250
Prior	1,831,970	1,657,885
Revolving Loans	400,894	317,728
Revolving Loans to Term Loans	457	426
Total	7,624,534	6,328,931
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | One-to-four family
Financing Receivable, Credit Quality Indicator [Line Items]
2022	829,363	793,848
2021	836,996	298,815
2020	294,721	197,707
2019	177,795	139,635
2018	125,377	135,171
Prior	595,932	527,141
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	2,860,184	2,092,317
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]
2022	829,363	793,848
2021	836,355	298,815
2020	294,721	196,244
2019	177,114	138,215
2018	125,057	134,811
Prior	595,097	525,615
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	2,857,707	2,087,548
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]
2022	0	0
2021	0	0
2020	0	0
2019	0	0
2018	0	0
Prior	0	203
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	0	203
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]
2022	0	0
2021	641	0
2020	0	1,463
2019	681	1,420
2018	320	360
Prior	835	1,323
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	2,477	4,566
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Multifamily
Financing Receivable, Credit Quality Indicator [Line Items]
2022	315,157	312,738
2021	309,611	181,285
2020	167,955	231,252
2019	205,608	47,024
2018	38,849	131,169
Prior	202,027	137,640
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	1,239,207	1,041,108
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Multifamily | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2022	315,157	312,738
2021	309,611	181,285
2020	167,955	231,252
2019	205,608	47,024
2018	38,849	131,169
Prior	197,489	137,640
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	1,234,669	1,041,108
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Multifamily | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	0
2019	0	0
2018	0	0
Prior	4,538	0
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	4,538	0
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Multifamily | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	0
2019	0	0
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]
2022	448,313	381,222
2021	393,167	161,522
2020	173,254	279,884
2019	262,767	259,300
2018	247,366	225,913
Prior	888,527	862,395
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	2,413,394	2,170,236
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Commercial real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2022	448,313	381,222
2021	392,689	161,136
2020	170,125	278,581
2019	260,268	241,669
2018	231,868	222,752
Prior	852,104	803,945
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	2,355,367	2,089,305
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]
2022	0	0
2021	478	0
2020	1,843	1,303
2019	892	16,070
2018	15,498	1,885
Prior	20,939	34,788
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	39,650	54,046
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Commercial real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	386
2020	1,286	0
2019	1,607	1,561
2018	0	1,276
Prior	15,484	23,662
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	18,377	26,885
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
2022	159,751	107,070
2021	104,339	77,549
2020	28,058	37,605
2019	14,216	41,591
2018	870	28,814
Prior	29,319	2,418
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	336,553	295,047
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Construction | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2022	159,751	107,070
2021	104,339	77,549
2020	28,058	37,498
2019	14,216	41,591
2018	870	28,814
Prior	29,319	2,418
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	336,553	294,940
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Construction | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	107
2019	0	0
2018	0	0
Prior	0	0
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	0	107
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Construction | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	0
2019	0	0
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]
2022	58,631	84,551
2021	33,214	36,201
2020	32,911	27,237
2019	21,842	33,123
2018	27,749	22,151
Prior	27,630	27,170
Revolving Loans	295,492	221,799
Revolving Loans to Term Loans	0	0
Total	497,469	452,232
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Commercial business loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2022	58,631	84,113
2021	32,880	36,115
2020	32,788	25,156
2019	20,705	30,670
2018	24,634	21,762
Prior	27,277	26,515
Revolving Loans	280,857	210,597
Revolving Loans to Term Loans	0	0
Total	477,772	434,928
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Commercial business loans | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	246
2021	110	15
2020	63	1,729
2019	1,137	1,369
2018	1,030	18
Prior	38	46
Revolving Loans	10,761	3,291
Revolving Loans to Term Loans	0	0
Total	13,139	6,714
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Commercial business loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	192
2021	224	71
2020	60	352
2019	0	1,084
2018	2,085	371
Prior	315	609
Revolving Loans	3,874	7,911
Revolving Loans to Term Loans	0	0
Total	6,558	10,590
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Consumer loans | Home equity loans and advances
Financing Receivable, Credit Quality Indicator [Line Items]
2022	22,903	22,393
2021	20,476	15,977
2020	13,770	15,906
2019	12,070	13,146
2018	11,126	12,023
Prior	88,439	101,116
Revolving Loans	105,061	95,576
Revolving Loans to Term Loans	457	426
Total	274,302	276,563
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]
2022	22,903	22,393
2021	20,476	15,977
2020	13,770	15,906
2019	12,070	13,146
2018	11,126	12,023
Prior	88,251	100,870
Revolving Loans	105,005	95,484
Revolving Loans to Term Loans	457	426
Total	274,058	276,225
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]
2022	0	0
2021	0	0
2020	0	0
2019	0	0
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]
2022	0	0
2021	0	0
2020	0	0
2019	0	0
2018	0	0
Prior	188	246
Revolving Loans	56	92
Revolving Loans to Term Loans	0	0
Total	244	338
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Consumer loans | Other consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
2022	2,669	659
2021	87	58
2020	100	284
2019	102	60
2018	30	9
Prior	96	5
Revolving Loans	341	353
Revolving Loans to Term Loans	0	0
Total	3,425	1,428
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Consumer loans | Other consumer loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2022	2,669	659
2021	87	58
2020	100	284
2019	102	60
2018	30	9
Prior	96	5
Revolving Loans	341	353
Revolving Loans to Term Loans	0	0
Total	3,425	1,428
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Consumer loans | Other consumer loans | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	0
2019	0	0
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]
2022	0	0
2021	0	0
2020	0	0
2019	0	0
2018	0	0
Prior	0	0
Revolving Loans	0	0
Revolving Loans to Term Loans	0	0
Total	$ 0	$ 0