Loan Portfolio and Allowance for Credit Losses, Risk Category of Loans (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Credit Risk Profile, Segregated by Class [Abstract]
Total loans		$ 4,540,559		$ 4,540,559
Total loans, net						$ 4,438,779
Current-period Gross writeoffs		30	$ 21	77	$ 116
Impaired loans included in classified loans						226
New York and Other States [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans	[1]	3,152,645		3,152,645
Total loans, net	[1]					3,132,378
Current-period Gross writeoffs	[1]	30	21	77	114
Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans		1,387,914		1,387,914
Total loans, net						1,306,401
Current-period Gross writeoffs		0	0	0	2
Commercial [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans		199,886		199,886
Total loans, net						200,200
Current-period Gross writeoffs		4	0	40	0
Commercial [Member] | New York and Other States [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans, net						177,952
Current-period Gross writeoffs	[1]	4	0	40	0
Commercial [Member] | Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans, net						22,248
Current-period Gross writeoffs		0	0	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						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						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		24,830		24,830
2021		32,586		32,586
2020		24,652		24,652
2019		24,684		24,684
2018		20,588		20,588
Prior		44,602		44,602
Revolving Loans Amortized Cost Basis		7,682		7,682
Revolving Loan Converted to Term		0		0
Total loans		179,624		179,624
Total loans, net						168,716
2022				0
2021				0
2020				0
2019				0
2018				0
Prior				40
Revolving Loans Amortized Cost Basis Writeoffs				0
Revolving Loan Converted to Term Writeoffs				0
Current-period Gross writeoffs				40
Commercial [Member] | Commercial Real Estate [Member] | New York and Other States [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans	[1]	151,978		151,978
Total loans, net	[1]					147,063
Commercial [Member] | Commercial Real Estate [Member] | Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans		27,646		27,646
Total loans, net						21,653
Commercial [Member] | Commercial Real Estate [Member] | Pass [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		24,830		24,830
2021		32,586		32,586
2020		24,467		24,467
2019		24,684		24,684
2018		20,201		20,201
Prior		43,368		43,368
Revolving Loans Amortized Cost Basis		7,682		7,682
Revolving Loan Converted to Term		0		0
Total loans		177,818		177,818
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						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		0
2021		0		0
2020		69		69
2019		0		0
2018		251		251
Prior		0		0
Revolving Loans Amortized Cost Basis		0		0
Revolving Loan Converted to Term		0		0
Total loans		320		320
Commercial [Member] | Commercial Real Estate [Member] | Substandard [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		0		0
2021		0		0
2020		116		116
2019		0		0
2018		136		136
Prior		1,234		1,234
Revolving Loans Amortized Cost Basis		0		0
Revolving Loan Converted to Term		0		0
Total loans		1,486		1,486
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						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		1,325		1,325
2021		3,962		3,962
2020		3,028		3,028
2019		722		722
2018		823		823
Prior		2,535		2,535
Revolving Loans Amortized Cost Basis		7,867		7,867
Revolving Loan Converted to Term		0		0
Total loans		20,262		20,262
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]	19,134		19,134
Total loans, net	[1]					30,889
Commercial [Member] | Other [Member] | Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans		1,128		1,128
Total loans, net						595
Commercial [Member] | Other [Member] | Pass [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		1,325		1,325
2021		3,623		3,623
2020		3,028		3,028
2019		722		722
2018		823		823
Prior		2,535		2,535
Revolving Loans Amortized Cost Basis		7,729		7,729
Revolving Loan Converted to Term		0		0
Total loans		19,785		19,785
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						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		0
2021		316		316
2020		0		0
2019		0		0
2018		0		0
Prior		0		0
Revolving Loans Amortized Cost Basis		40		40
Revolving Loan Converted to Term		0		0
Total loans		356		356
Commercial [Member] | Other [Member] | Substandard [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		0		0
2021		23		23
2020		0		0
2019		0		0
2018		0		0
Prior		0		0
Revolving Loans Amortized Cost Basis		98		98
Revolving Loan Converted to Term		0		0
Total loans		121		121
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						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		4,330,415		4,330,415
Total loans, net						4,229,163
Current-period Gross writeoffs		12	20	12	106
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]	12	20	12	106
Real Estate Mortgage - 1 to 4 Family [Member] | Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Current-period Gross writeoffs		0	0	0	0
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		280,214		280,214
2021		965,330		965,330
2020		815,623		815,623
2019		383,119		383,119
2018		269,606		269,606
Prior		1,303,372		1,303,372
Revolving Loans Amortized Cost Basis		1,114		1,114
Revolving Loan Converted to Term		0		0
Total loans		4,018,378		4,018,378
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]	2,747,210		2,747,210
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		1,271,168		1,271,168
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		280,214		280,214
2021		965,157		965,157
2020		815,540		815,540
2019		382,448		382,448
2018		268,833		268,833
Prior		1,289,409		1,289,409
Revolving Loans Amortized Cost Basis		1,114		1,114
Revolving Loan Converted to Term		0		0
Total loans		4,002,715		4,002,715
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | Nonperforming [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		0		0
2021		173		173
2020		83		83
2019		671		671
2018		773		773
Prior		13,963		13,963
Revolving Loans Amortized Cost Basis		0		0
Revolving Loan Converted to Term		0		0
Total loans		15,663		15,663
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		3,335		3,335
2021		10,166		10,166
2020		7,031		7,031
2019		8,108		8,108
2018		5,718		5,718
Prior		23,921		23,921
Revolving Loans Amortized Cost Basis		0		0
Revolving Loan Converted to Term		0		0
Total loans		58,279		58,279
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]	45,428		45,428
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		12,851		12,851
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		3,335		3,335
2021		10,166		10,166
2020		7,031		7,031
2019		8,108		8,108
2018		5,718		5,718
Prior		23,751		23,751
Revolving Loans Amortized Cost Basis		0		0
Revolving Loan Converted to Term		0		0
Total loans		58,109		58,109
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | Nonperforming [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		0		0
2021		0		0
2020		0		0
2019		0		0
2018		0		0
Prior		170		170
Revolving Loans Amortized Cost Basis		0		0
Revolving Loan Converted to Term		0		0
Total loans		170		170
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		660		660
2021		847		847
2020		414		414
2019		70		70
2018		94		94
Prior		21,819		21,819
Revolving Loans Amortized Cost Basis		229,854		229,854
Revolving Loan Converted to Term		0		0
Total loans		253,758		253,758
Total loans, net						230,976
2022				0
2021				0
2020				0
2019				0
2018				0
Prior				12
Revolving Loans Amortized Cost Basis Writeoffs				0
Revolving Loan Converted to Term Writeoffs				0
Current-period Gross writeoffs				12
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]	180,720		180,720
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		73,038		73,038
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		660		660
2021		847		847
2020		414		414
2019		70		70
2018		94		94
Prior		19,266		19,266
Revolving Loans Amortized Cost Basis		229,789		229,789
Revolving Loan Converted to Term		0		0
Total loans		251,140		251,140
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		0
2021		0		0
2020		0		0
2019		0		0
2018		0		0
Prior		2,553		2,553
Revolving Loans Amortized Cost Basis		65		65
Revolving Loan Converted to Term		0		0
Total loans		2,618		2,618
Installment [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		2,503		2,503
2021		3,047		3,047
2020		1,099		1,099
2019		1,221		1,221
2018		581		581
Prior		691		691
Revolving Loans Amortized Cost Basis		1,116		1,116
Revolving Loan Converted to Term		0		0
Total loans		10,258		10,258
Total loans, net						9,416
2022				0
2021				13
2020				5
2019				6
2018				0
Prior				1
Revolving Loans Amortized Cost Basis Writeoffs				0
Revolving Loan Converted to Term Writeoffs				0
Current-period Gross writeoffs		14	1	25	10
Installment [Member] | New York and Other States [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans	[1]	8,175		8,175
Total loans, net	[1]					7,368
Current-period Gross writeoffs	[1]	14	1	25	8
Installment [Member] | Florida [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Total loans		2,083		2,083
Total loans, net						$ 2,048
Current-period Gross writeoffs		0	$ 0	0	$ 2
Installment [Member] | Performing [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		2,503		2,503
2021		3,047		3,047
2020		1,099		1,099
2019		1,200		1,200
2018		581		581
Prior		690		690
Revolving Loans Amortized Cost Basis		1,093		1,093
Revolving Loan Converted to Term		0		0
Total loans		10,213		10,213
Installment [Member] | Nonperforming [Member]
Credit Risk Profile, Segregated by Class [Abstract]
2022		0		0
2021		0		0
2020		0		0
2019		21		21
2018		0		0
Prior		1		1
Revolving Loans Amortized Cost Basis		23		23
Revolving Loan Converted to Term		0		0
Total loans		$ 45		$ 45

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