Loans Receivable and Allowance for Credit Losses (Summary of Aging Loans Receivable by Portfolio Segment and Class) (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	$ 10,542,352	$ 10,261,645
Non-accrual	45,928	58,509
Recorded Investment greater than 90 days accruing	0	0
Total Past Due	59,176	69,548
Non-accrual loans with no related allowance	30,544	50,227
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	4,373,436	4,316,185
Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	1,645,770	1,513,818
Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	707,234	715,494
Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	1,166,159	1,177,698
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	10,703	7,255
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	2,545	3,784
Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	10,483,176	10,192,097
Mortgage loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	7,892,599	7,723,195
Non-accrual	13,165	33,583
Recorded Investment greater than 90 days accruing	0	0
Total Past Due	22,198	41,612
Non-accrual loans with no related allowance	10,162	28,332
Mortgage loans | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	4,373,436	4,316,185
Non-accrual	7,279	28,212
Recorded Investment greater than 90 days accruing	0	0
Total Past Due	9,861	30,924
Non-accrual loans with no related allowance	4,276	22,961
Mortgage loans | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	1,645,770	1,513,818
Non-accrual	2,314	1,565
Recorded Investment greater than 90 days accruing	0	0
Total Past Due	6,167	2,355
Non-accrual loans with no related allowance	2,314	1,565
Mortgage loans | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	707,234	715,494
Non-accrual	1,874	1,878
Recorded Investment greater than 90 days accruing	0	0
Total Past Due	1,874	3,880
Non-accrual loans with no related allowance	1,874	1,878
Mortgage loans | Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	1,166,159	1,177,698
Non-accrual	1,698	1,928
Recorded Investment greater than 90 days accruing	0	0
Total Past Due	4,296	4,453
Non-accrual loans with no related allowance	1,698	1,928
Mortgage loans | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	6,725	5,406
Mortgage loans | 30-59 Days Past Due | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	1,445	2,300
Mortgage loans | 30-59 Days Past Due | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	3,853	790
Mortgage loans | 30-59 Days Past Due | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	0	905
Mortgage loans | 30-59 Days Past Due | Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	1,427	1,411
Mortgage loans | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	2,308	2,623
Mortgage loans | 60-89 Days Past Due | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	1,137	412
Mortgage loans | 60-89 Days Past Due | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	0	0
Mortgage loans | 60-89 Days Past Due | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	0	1,097
Mortgage loans | 60-89 Days Past Due | Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	1,171	1,114
Mortgage loans | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	7,870,401	7,681,583
Mortgage loans | Current | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	4,363,575	4,285,261
Mortgage loans | Current | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	1,639,603	1,511,463
Mortgage loans | Current | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	705,360	711,614
Mortgage loans | Current | Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	1,161,863	1,173,245
Commercial loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	2,348,447	2,233,670
Non-accrual	31,885	24,188
Recorded Investment greater than 90 days accruing	0	0
Total Past Due	34,996	26,166
Non-accrual loans with no related allowance	19,504	21,156
Commercial loans | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	3,021	964
Commercial loans | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	90	1,014
Commercial loans | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	2,313,451	2,207,504
Consumer loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	301,306	304,780
Non-accrual	878	738
Recorded Investment greater than 90 days accruing	0	0
Total Past Due	1,982	1,770
Non-accrual loans with no related allowance	878	739
Consumer loans | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	957	885
Consumer loans | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	147	147
Consumer loans | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total gross loans	$ 299,324	$ 303,010