Loans Receivable and Allowance for Credit Losses (Summary of Loans Receivable by Credit Quality Risk Rating Indicator- Current Year) (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
2024	$ 240,982	$ 1,506,562
2023	1,233,971	1,910,013
2022	1,942,094	1,615,910
2021	1,639,778	1,181,963
2020	1,196,577	963,225
Prior to 2020	3,746,268	2,870,710
Revolving Loans	737,912	716,838
Revolving loans to term loans	115,382	119,462
Total gross loans	10,852,964	10,884,683
Total classified and criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2024	440	11,882
2023	1,813	27,934
2022	46,372	32,648
2021	25,576	40,155
2020	40,300	12,753
Prior to 2020	76,244	81,269
Revolving Loans	33,094	39,570
Revolving loans to term loans	2,439	1,285
Total gross loans	226,278	247,496
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	450
2023	0	27,934
2022	30,219	12,386
2021	5,056	30,920
2020	29,177	10,710
Prior to 2020	47,547	58,155
Revolving Loans	12,870	28,011
Revolving loans to term loans	1,853	687
Total gross loans	126,722	169,253
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2024	440	4,421
2023	1,813	0
2022	16,153	20,262
2021	20,520	9,235
2020	11,123	2,043
Prior to 2020	28,697	23,114
Revolving Loans	20,224	11,559
Revolving loans to term loans	586	598
Total gross loans	99,556	71,232
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	7,011
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	0	0
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	0	7,011
Loss
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	0	0
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	0	0
Pass/Watch
Financing Receivable, Credit Quality Indicator [Line Items]
2024	240,542	1,494,680
2023	1,232,158	1,882,079
2022	1,895,722	1,583,262
2021	1,614,202	1,141,808
2020	1,156,277	950,472
Prior to 2020	3,670,024	2,789,441
Revolving Loans	704,818	677,268
Revolving loans to term loans	112,943	118,177
Total gross loans	10,626,686	10,637,187
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2024	82,138	629,191
2023	467,001	894,075
2022	882,465	680,512
2021	717,180	498,768
2020	468,331	481,529
Prior to 2020	1,638,052	1,200,402
Revolving Loans	86,303	95,694
Revolving loans to term loans	12,329	32,240
Total gross loans	4,353,799	4,512,411
Commercial \| Total classified and criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	482
2023	0	10,926
2022	10,807	3,048
2021	3,027	28,511
2020	27,854	10,558
Prior to 2020	23,102	34,197
Revolving Loans	434	4,934
Revolving loans to term loans	0	0
Total gross loans	65,224	92,656
Commercial \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	10,926
2022	10,807	3,048
2021	3,027	28,511
2020	27,854	10,558
Prior to 2020	10,185	24,598
Revolving Loans	0	4,500
Revolving loans to term loans	0	0
Total gross loans	51,873	82,141
Commercial \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	482
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	12,917	9,599
Revolving Loans	434	434
Revolving loans to term loans	0	0
Total gross loans	13,351	10,515
Commercial \| Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	0	0
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	0	0
Commercial \| Loss
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	0	0
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	0	0
Commercial \| Pass/Watch
Financing Receivable, Credit Quality Indicator [Line Items]
2024	82,138	628,709
2023	467,001	883,149
2022	871,658	677,464
2021	714,153	470,257
2020	440,477	470,971
Prior to 2020	1,614,950	1,166,205
Revolving Loans	85,869	90,760
Revolving loans to term loans	12,329	32,240
Total gross loans	4,288,575	4,419,755
Multi-family
Financing Receivable, Credit Quality Indicator [Line Items]
2024	38,438	344,095
2023	270,000	172,244
2022	171,591	184,136
2021	237,488	271,878
2020	290,644	230,456
Prior to 2020	810,834	601,970
Revolving Loans	5,299	6,115
Revolving loans to term loans	1,594	1,606
Total gross loans	1,825,888	1,812,500
Multi-family \| Total classified and criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	3,253
2023	1,630	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	8,398	9,500
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	10,028	12,753
Multi-family \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022		0
2021		0
2020	0	0
Prior to 2020	7,672	9,500
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	7,672	9,500
Multi-family \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	3,253
2023	1,630	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	726	0
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	2,356	3,253
Multi-family \| Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	0	0
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	0	0
Multi-family \| Loss
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	0	0
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	0	0
Multi-family \| Pass/Watch
Financing Receivable, Credit Quality Indicator [Line Items]
2024	38,438	340,842
2023	268,370	172,244
2022	171,591	184,136
2021	237,488	271,878
2020	290,644	230,456
Prior to 2020	802,436	592,470
Revolving Loans	5,299	6,115
Revolving loans to term loans	1,594	1,606
Total gross loans	1,815,860	1,799,747
Construction
Financing Receivable, Credit Quality Indicator [Line Items]
2024	9,304	41,209
2023	70,036	342,890
2022	359,176	185,034
2021	189,056	68,603
2020	68,915	1,339
Prior to 2020	14,930	14,171
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	711,417	653,246
Construction \| Total classified and criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	0	771
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	0	771
Construction \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	0	0
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	0	0
Construction \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	0	771
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	0	771
Construction \| Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	0	0
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	0	0
Construction \| Loss
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	0	0
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	0	0
Construction \| Pass/Watch
Financing Receivable, Credit Quality Indicator [Line Items]
2024	9,304	41,209
2023	70,036	342,890
2022	359,176	185,034
2021	189,056	68,603
2020	68,915	1,339
Prior to 2020	14,930	13,400
Revolving Loans		0
Revolving loans to term loans	0	0
Total gross loans	711,417	652,475
Residential
Financing Receivable, Credit Quality Indicator [Line Items]
2024	9,893	96,259
2023	95,128	141,683
2022	139,459	200,111
2021	197,548	195,964
2020	192,575	89,654
Prior to 2020	517,582	441,285
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	1,152,185	1,164,956
Residential \| Total classified and criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	2,451	2,493
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	2,451	2,493
Residential \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	804	1,208
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	804	1,208
Residential \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	1,647	1,285
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	1,647	1,285
Residential \| Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	0	0
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	0	0
Residential \| Loss
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	0	0
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	0	0
Residential \| Pass/Watch
Financing Receivable, Credit Quality Indicator [Line Items]
2024	9,893	96,259
2023	95,128	141,683
2022	139,459	200,111
2021	197,548	195,964
2020	192,575	89,654
Prior to 2020	515,131	438,792
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	1,149,734	1,162,463
Commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
2024	97,643	366,725
2023	304,354	333,023
2022	363,617	348,016
2021	280,563	143,291
2020	172,715	145,863
Prior to 2020	669,464	527,256
Revolving Loans	537,957	506,031
Revolving loans to term loans	88,237	72,201
Total gross loans	2,514,550	2,442,406
Commercial loans \| Total classified and criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2024	440	8,147
2023	183	17,008
2022	35,565	29,600
2021	22,549	11,644
2020	12,446	2,186
Prior to 2020	41,961	34,065
Revolving Loans	31,610	34,069
Revolving loans to term loans	2,306	1,195
Total gross loans	147,060	137,914
Commercial loans \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	450
2023	0	17,008
2022	19,412	9,338
2021	2,029	2,409
2020	1,323	152
Prior to 2020	28,836	22,752
Revolving Loans	12,208	23,333
Revolving loans to term loans	1,810	687
Total gross loans	65,618	76,129
Commercial loans \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2024	440	686
2023	183	0
2022	16,153	20,262
2021	20,520	9,235
2020	11,123	2,034
Prior to 2020	13,125	11,313
Revolving Loans	19,402	10,736
Revolving loans to term loans	496	508
Total gross loans	81,442	54,774
Commercial loans \| Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	7,011
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	0	0
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	0	7,011
Commercial loans \| Loss
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	0	0
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	0	0
Commercial loans \| Pass/Watch
Financing Receivable, Credit Quality Indicator [Line Items]
2024	97,203	358,578
2023	304,171	316,015
2022	328,052	318,416
2021	258,014	131,647
2020	160,269	143,677
Prior to 2020	627,503	493,191
Revolving Loans	506,347	471,962
Revolving loans to term loans	85,931	71,006
Total gross loans	2,367,490	2,304,492
Consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
2024	3,566	29,083
2023	27,452	26,098
2022	25,786	18,101
2021	17,943	3,459
2020	3,397	14,384
Prior to 2020	95,406	85,626
Revolving Loans	108,353	108,998
Revolving loans to term loans	13,222	13,415
Total gross loans	295,125	299,164
Consumer loans \| Total classified and criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	9
Prior to 2020	332	243
Revolving Loans	1,050	567
Revolving loans to term loans	133	90
Total gross loans	1,515	909
Consumer loans \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior to 2020	50	97
Revolving Loans	662	178
Revolving loans to term loans	43	0
Total gross loans	755	275
Consumer loans \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0

Loans Receivable and Allowance for Credit Losses (Summary of Loans Receivable by Credit Quality Risk Rating Indicator- Current Year) (Detail) - USD ($)
$ in Thousands