Loan Portfolio and Allowance for Credit Losses, Risk Category of Loans (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Credit Risk Profile, Segregated by Class [Abstract]
Total loans		$ 4,464,354
Total loans, net				$ 4,438,779
Current-period Gross writeoffs		47	$ 95
Impaired loans included in classified loans				226
New York and Other States [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans	[1]	3,123,916
Total loans, net	[1]			3,132,378
Current-period Gross writeoffs	[1]	46	93
Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans		1,340,438
Total loans, net				1,306,401
Current-period Gross writeoffs		1	2
Commercial [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans		192,408
Total loans, net				200,200
Current-period Gross writeoffs		36	0
Commercial [Member] | New York and Other States [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans, net	[2]			177,952
Current-period Gross writeoffs	[1]	36	0
Commercial [Member] | Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans, net				22,248
Current-period Gross writeoffs		0	0
Commercial [Member] | Pass [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans, net				197,934
Commercial [Member] | Pass [Member] | New York and Other States [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans, net	[2]			176,226
Commercial [Member] | Pass [Member] | Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans, net				21,708
Commercial [Member] | Classified [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans, net				2,266
Commercial [Member] | Classified [Member] | New York and Other States [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans, net	[2]			1,726
Commercial [Member] | Classified [Member] | Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans, net				540
Commercial [Member] | Commercial Real Estate [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		10,701
2021		32,756
2020		24,602
2019		26,575
2018		21,295
Prior		47,877
Revolving Loans Amortized Cost Basis		7,424
Revolving Loan Converted to Term		0
Total loans		171,230
Total loans, net				168,716
2022		0
2021		0
2020		0
2019		0
2018		0
Prior		36
Revolving Loans Amortized Cost Basis Writeoffs		0
Revolving Loan Converted to Term Writeoffs		0
Current-period Gross writeoffs		36
Commercial [Member] | Commercial Real Estate [Member] | New York and Other States [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans	[1]	147,295
Total loans, net	[1],[2]			147,063
Commercial [Member] | Commercial Real Estate [Member] | Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans		23,935
Total loans, net				21,653
Commercial [Member] | Commercial Real Estate [Member] | Pass [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		10,701
2021		32,756
2020		24,411
2019		26,575
2018		20,900
Prior		46,493
Revolving Loans Amortized Cost Basis		7,424
Revolving Loan Converted to Term		0
Total loans		169,260
Total loans, net				166,613
Commercial [Member] | Commercial Real Estate [Member] | Pass [Member] | New York and Other States [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans, net	[2]			145,500
Commercial [Member] | Commercial Real Estate [Member] | Pass [Member] | Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans, net				21,113
Commercial [Member] | Commercial Real Estate [Member] | Special Mention [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		0
2021		0
2020		73
2019		0
2018		255
Prior		0
Revolving Loans Amortized Cost Basis		0
Revolving Loan Converted to Term		0
Total loans		328
Commercial [Member] | Commercial Real Estate [Member] | Substandard [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		0
2021		0
2020		118
2019		0
2018		140
Prior		1,384
Revolving Loans Amortized Cost Basis		0
Revolving Loan Converted to Term		0
Total loans		1,642
Commercial [Member] | Commercial Real Estate [Member] | Classified [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans, net				2,103
Commercial [Member] | Commercial Real Estate [Member] | Classified [Member] | New York and Other States [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans, net	[2]			1,563
Commercial [Member] | Commercial Real Estate [Member] | Classified [Member] | Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans, net				540
Commercial [Member] | Other [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		419
2021		6,276
2020		3,301
2019		786
2018		956
Prior		2,735
Revolving Loans Amortized Cost Basis		6,705
Revolving Loan Converted to Term		0
Total loans		21,178
Total loans, net				31,484
2022		0
2021		0
2020		0
2019		0
2018		0
Prior		0
Revolving Loans Amortized Cost Basis Writeoffs		0
Revolving Loan Converted to Term Writeoffs		0
Current-period Gross writeoffs		0
Commercial [Member] | Other [Member] | New York and Other States [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans	[1]	20,198
Total loans, net	[1],[2]			30,889
Commercial [Member] | Other [Member] | Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans		980
Total loans, net				595
Commercial [Member] | Other [Member] | Pass [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		419
2021		5,931
2020		3,301
2019		786
2018		956
Prior		2,634
Revolving Loans Amortized Cost Basis		6,705
Revolving Loan Converted to Term		0
Total loans		20,732
Total loans, net				31,321
Commercial [Member] | Other [Member] | Pass [Member] | New York and Other States [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans, net	[2]			30,726
Commercial [Member] | Other [Member] | Pass [Member] | Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans, net				595
Commercial [Member] | Other [Member] | Special Mention [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		0
2021		320
2020		0
2019		0
2018		0
Prior		0
Revolving Loans Amortized Cost Basis		0
Revolving Loan Converted to Term		0
Total loans		320
Commercial [Member] | Other [Member] | Substandard [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		0
2021		25
2020		0
2019		0
2018		0
Prior		101
Revolving Loans Amortized Cost Basis		0
Revolving Loan Converted to Term		0
Total loans		126
Commercial [Member] | Other [Member] | Classified [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans, net				163
Commercial [Member] | Other [Member] | Classified [Member] | New York and Other States [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans, net	[2]			163
Commercial [Member] | Other [Member] | Classified [Member] | Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans, net				0
Real Estate Mortgage - 1 to 4 Family [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans		4,262,551
Total loans, net				4,229,163
Current-period Gross writeoffs		0	86
Real Estate Mortgage - 1 to 4 Family [Member] | New York and Other States [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Current-period Gross writeoffs	[1]	0	86
Real Estate Mortgage - 1 to 4 Family [Member] | Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Current-period Gross writeoffs		0	0
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		142,158
2021		971,838
2020		834,714
2019		393,388
2018		279,787
Prior		1,343,532
Revolving Loans Amortized Cost Basis		545
Revolving Loan Converted to Term		0
Total loans		3,965,962
Total loans, net				3,936,302
2022		0
2021		0
2020		0
2019		0
2018		0
Prior		0
Revolving Loans Amortized Cost Basis Writeoffs		0
Revolving Loan Converted to Term Writeoffs		0
Current-period Gross writeoffs		0
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | New York and Other States [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans	[1]	2,729,257
Total loans, net	[1]			2,723,734
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans		1,236,705
Total loans, net				1,212,568
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | Performing [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		142,158
2021		971,838
2020		834,631
2019		392,717
2018		279,365
Prior		1,328,713
Revolving Loans Amortized Cost Basis		545
Revolving Loan Converted to Term		0
Total loans		3,949,967
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | Nonperforming [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		0
2021		0
2020		83
2019		671
2018		422
Prior		14,819
Revolving Loans Amortized Cost Basis		0
Revolving Loan Converted to Term		0
Total loans		15,995
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		2,414
2021		10,463
2020		7,431
2019		8,589
2018		6,078
Prior		25,497
Revolving Loans Amortized Cost Basis		0
Revolving Loan Converted to Term		0
Total loans		60,472
Total loans, net				61,885
2022		0
2021		0
2020		0
2019		0
2018		0
Prior		0
Revolving Loans Amortized Cost Basis Writeoffs		0
Revolving Loan Converted to Term Writeoffs		0
Current-period Gross writeoffs		0
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | New York and Other States [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans	[1]	47,043
Total loans, net	[1]			48,190
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans		13,429
Total loans, net				13,695
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | Performing [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		2,414
2021		10,463
2020		7,431
2019		8,589
2018		5,943
Prior		25,324
Revolving Loans Amortized Cost Basis		0
Revolving Loan Converted to Term		0
Total loans		60,164
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | Nonperforming [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		0
2021		0
2020		0
2019		0
2018		135
Prior		173
Revolving Loans Amortized Cost Basis		0
Revolving Loan Converted to Term		0
Total loans		308
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		221
2021		721
2020		492
2019		100
2018		70
Prior		22,453
Revolving Loans Amortized Cost Basis		212,060
Revolving Loan Converted to Term		0
Total loans		236,117
Total loans, net				230,976
2022		0
2021		0
2020		0
2019		0
2018		0
Prior		0
Revolving Loans Amortized Cost Basis Writeoffs		0
Revolving Loan Converted to Term Writeoffs		0
Current-period Gross writeoffs		0
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | New York and Other States [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans	[1]	172,854
Total loans, net	[1]			175,134
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans		63,263
Total loans, net				55,842
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | Performing [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		221
2021		721
2020		492
2019		100
2018		70
Prior		19,850
Revolving Loans Amortized Cost Basis		211,792
Revolving Loan Converted to Term		0
Total loans		233,246
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | Nonperforming [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		0
2021		0
2020		0
2019		0
2018		0
Prior		2,603
Revolving Loans Amortized Cost Basis		268
Revolving Loan Converted to Term		0
Total loans		2,871
Installment [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		937
2021		3,421
2020		1,327
2019		1,498
2018		686
Prior		375
Revolving Loans Amortized Cost Basis		1,151
Revolving Loan Converted to Term		0
Total loans		9,395
Total loans, net				9,416
2022		0
2021		0
2020		5
2019		5
2018		0
Prior		1
Revolving Loans Amortized Cost Basis Writeoffs		0
Revolving Loan Converted to Term Writeoffs		0
Current-period Gross writeoffs		11	9
Installment [Member] | New York and Other States [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans	[1]	7,269
Total loans, net	[1]			7,368
Current-period Gross writeoffs	[1]	10	7
Installment [Member] | Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans		2,126
Total loans, net				$ 2,048
Current-period Gross writeoffs		1	$ 2
Installment [Member] | Performing [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		937
2021		3,409
2020		1,326
2019		1,471
2018		686
Prior		375
Revolving Loans Amortized Cost Basis		1,150
Revolving Loan Converted to Term		0
Total loans		9,354
Installment [Member] | Nonperforming [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		0
2021		12
2020		1
2019		27
2018		0
Prior		0
Revolving Loans Amortized Cost Basis		1
Revolving Loan Converted to Term		0
Total loans		$ 41

[1] Includes New York, New Jersey, Vermont and Massachusetts.

[2] Includes New York, New Jersey and Massachusetts.