Loans Receivable and Allowance for Credit Losses (Summary of Loans Receivable by Credit Quality Risk Rating Indicator-Prior Year) (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
2023	$ 240,982	$ 1,506,562
2022	1,233,971	1,910,013
2021	1,942,094	1,615,910
2020	1,639,778	1,181,963
2019	1,196,577	963,225
Prior to 2019	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]
2023	440	11,882
2022	1,813	27,934
2021	46,372	32,648
2020	25,576	40,155
2019	40,300	12,753
Prior to 2019	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]
2023	0	450
2022	0	27,934
2021	30,219	12,386
2020	5,056	30,920
2019	29,177	10,710
Prior to 2019	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]
2023	440	4,421
2022	1,813	0
2021	16,153	20,262
2020	20,520	9,235
2019	11,123	2,043
Prior to 2019	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]
2023	0	7,011
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	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]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	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]
2023	240,542	1,494,680
2022	1,232,158	1,882,079
2021	1,895,722	1,583,262
2020	1,614,202	1,141,808
2019	1,156,277	950,472
Prior to 2019	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]
2023	82,138	629,191
2022	467,001	894,075
2021	882,465	680,512
2020	717,180	498,768
2019	468,331	481,529
Prior to 2019	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]
2023	0	482
2022	0	10,926
2021	10,807	3,048
2020	3,027	28,511
2019	27,854	10,558
Prior to 2019	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]
2023	0	0
2022	0	10,926
2021	10,807	3,048
2020	3,027	28,511
2019	27,854	10,558
Prior to 2019	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]
2023	0	482
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	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]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	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]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	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]
2023	82,138	628,709
2022	467,001	883,149
2021	871,658	677,464
2020	714,153	470,257
2019	440,477	470,971
Prior to 2019	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
Construction
Financing Receivable, Credit Quality Indicator [Line Items]
2023	9,304	41,209
2022	70,036	342,890
2021	359,176	185,034
2020	189,056	68,603
2019	68,915	1,339
Prior to 2019	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]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	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]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	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]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	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]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	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]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	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]
2023	9,304	41,209
2022	70,036	342,890
2021	359,176	185,034
2020	189,056	68,603
2019	68,915	1,339
Prior to 2019	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]
2023	9,893	96,259
2022	95,128	141,683
2021	139,459	200,111
2020	197,548	195,964
2019	192,575	89,654
Prior to 2019	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]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	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]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	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]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	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]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	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]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	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]
2023	9,893	96,259
2022	95,128	141,683
2021	139,459	200,111
2020	197,548	195,964
2019	192,575	89,654
Prior to 2019	515,131	438,792
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	1,149,734	1,162,463
Mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
2023	139,773	1,110,754
2022	902,165	1,550,892
2021	1,552,691	1,249,793
2020	1,341,272	1,035,213
2019	1,020,465	802,978
Prior to 2019	2,981,398	2,257,828
Revolving Loans	91,602	101,809
Revolving loans to term loans	13,923	33,846
Total gross loans	8,043,289	8,143,113
Mortgage loans | Total classified and criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	3,735
2022	1,630	10,926
2021	10,807	3,048
2020	3,027	28,511
2019	27,854	10,558
Prior to 2019	33,951	46,961
Revolving Loans	434	4,934
Revolving loans to term loans	0	0
Total gross loans	77,703	108,673
Mortgage loans | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022	0	10,926
2021	10,807	3,048
2020	3,027	28,511
2019	27,854	10,558
Prior to 2019	18,661	35,306
Revolving Loans	0	4,500
Revolving loans to term loans	0	0
Total gross loans	60,349	92,849
Mortgage loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	3,735
2022	1,630	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	15,290	11,655
Revolving Loans	434	434
Revolving loans to term loans	0	0
Total gross loans	17,354	15,824
Mortgage loans | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	0	0
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	0	0
Mortgage loans | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	0	0
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	0	0
Mortgage loans | Pass/Watch
Financing Receivable, Credit Quality Indicator [Line Items]
2023	139,773	1,107,019
2022	900,535	1,539,966
2021	1,541,884	1,246,745
2020	1,338,245	1,006,702
2019	992,611	792,420
Prior to 2019	2,947,447	2,210,867
Revolving Loans	91,168	96,875
Revolving loans to term loans	13,923	33,846
Total gross loans	7,965,586	8,034,440
Mortgage loans | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans	4,353,799	4,512,411
Mortgage loans | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans	711,417	653,246
Mortgage loans | Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans	1,152,185	1,164,956
Consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
2023	3,566	29,083
2022	27,452	26,098
2021	25,786	18,101
2020	17,943	3,459
2019	3,397	14,384
Prior to 2019	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]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	9
Prior to 2019	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]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	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]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	9
Prior to 2019	282	146
Revolving Loans	388	389
Revolving loans to term loans	90	90
Total gross loans	760	634
Consumer loans | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	0	0
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	0	0
Consumer loans | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior to 2019	0	0
Revolving Loans	0	0
Revolving loans to term loans	0	0
Total gross loans	0	0
Consumer loans | Pass/Watch
Financing Receivable, Credit Quality Indicator [Line Items]
2023	3,566	29,083
2022	27,452	26,098
2021	25,786	18,101
2020	17,943	3,459
2019	3,397	14,375
Prior to 2019	95,074	85,383
Revolving Loans	107,303	108,431
Revolving loans to term loans	13,089	13,325
Total gross loans	$ 293,610	$ 298,255