Loans Receivable and Allowance for Credit Losses (Summary of Aging Loans Receivable by Portfolio Segment and Class) (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	$ 10,852,964	$ 10,884,683
Non-accrual	47,592	49,639
Non-accrual loans with no related allowance	36,689	44,433
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	4,353,799	4,512,411
Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	1,825,888	1,812,500
Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	711,417	653,246
Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	1,152,185	1,164,956
Total Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	76,616	62,897
30-59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	25,985	9,942
60-89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	3,039	3,316
Recorded Investment > 90 days accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	0	0
Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	10,776,348	10,821,786
Mortgage loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	8,043,289	8,143,113
Non-accrual	9,940	7,519
Non-accrual loans with no related allowance	9,940	7,519
Mortgage loans | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	4,353,799	4,512,411
Non-accrual	5,938	5,151
Non-accrual loans with no related allowance	5,938	5,151
Mortgage loans | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	1,825,888	1,812,500
Non-accrual	2,355	744
Non-accrual loans with no related allowance	2,355	744
Mortgage loans | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	711,417	653,246
Non-accrual	0	771
Non-accrual loans with no related allowance	0	771
Mortgage loans | Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	1,152,185	1,164,956
Non-accrual	1,647	853
Non-accrual loans with no related allowance	1,647	853
Mortgage loans | Total Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	32,581	18,431
Mortgage loans | Total Past Due | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	12,138	5,976
Mortgage loans | Total Past Due | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	14,424	6,194
Mortgage loans | Total Past Due | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	0	771
Mortgage loans | Total Past Due | Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	6,019	5,490
Mortgage loans | 30-59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	20,689	8,069
Mortgage loans | 30-59 Days | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	5,052	825
Mortgage loans | 30-59 Days | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	12,069	3,815
Mortgage loans | 30-59 Days | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	0	0
Mortgage loans | 30-59 Days | Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	3,568	3,429
Mortgage loans | 60-89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	1,952	2,843
Mortgage loans | 60-89 Days | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	1,148	0
Mortgage loans | 60-89 Days | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	0	1,635
Mortgage loans | 60-89 Days | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	0	0
Mortgage loans | 60-89 Days | Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	804	1,208
Mortgage loans | Recorded Investment > 90 days accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	0	0
Mortgage loans | Recorded Investment > 90 days accruing | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	0	0
Mortgage loans | Recorded Investment > 90 days accruing | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans		0
Mortgage loans | Recorded Investment > 90 days accruing | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	0	0
Mortgage loans | Recorded Investment > 90 days accruing | Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	0	0
Mortgage loans | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	8,010,708	8,124,682
Mortgage loans | Current | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	4,341,661	4,506,435
Mortgage loans | Current | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	1,811,464	1,806,306
Mortgage loans | Current | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	711,417	652,475
Mortgage loans | Current | Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	1,146,166	1,159,466
Commercial loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	2,514,550	2,442,406
Non-accrual	36,892	41,487
Non-accrual loans with no related allowance	25,989	36,281
Commercial loans | Total Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	41,717	42,683
Commercial loans | 30-59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	4,493	998
Commercial loans | 60-89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	332	198
Commercial loans | Recorded Investment > 90 days accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	0	0
Commercial loans | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	2,472,833	2,399,723
Consumer loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	295,125	299,164
Non-accrual	760	633
Non-accrual loans with no related allowance	760	633
Consumer loans | Total Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	2,318	1,783
Consumer loans | 30-59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	803	875
Consumer loans | 60-89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	755	275
Consumer loans | Recorded Investment > 90 days accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	0	0
Consumer loans | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	$ 292,807	$ 297,381