Loans and Allowance for Loan Losses, Past Due (Details) - USD ($) $ in Thousands		3 Months Ended		12 Months Ended
		Mar. 31, 2021		Dec. 31, 2020
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		$ 17,913		$ 17,524
Current		4,251,259		4,226,946
Total loans		$ 4,269,172		$ 4,244,470
Number of days past due		90 days		90 days
Loans that are 90 days past due and still accruing interest		$ 0		$ 0
New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	15,497		15,923
Current	[1]	3,046,526		3,045,429
Total loans	[1]	3,062,023		3,061,352
Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		2,416		1,601
Current		1,204,733		1,181,517
Total loans		1,207,149		1,183,118
30-59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		3,400		2,241
30-59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	2,329		1,869
30-59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1,071		372
60-89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		806		1,931
60-89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	421		1,404
60-89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		385		527
90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		13,707		13,352
90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	12,747		12,650
90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		960		702
Commercial [Member]
Aging of the recorded investment in past due loans [Abstract]
Total loans		217,021		212,492
Commercial [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total loans		198,667	[2]	193,707
Commercial [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total loans		18,354		18,785
Commercial [Member] | Commercial Real Estate [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		324		481
Current		164,659		166,960
Total loans		164,983		167,441
Commercial [Member] | Commercial Real Estate [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	324		481
Current	[1]	146,670		148,294
Total loans	[1]	146,994	[2]	148,775
Commercial [Member] | Commercial Real Estate [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0		0
Current		17,989		18,666
Total loans		17,989		18,666
Commercial [Member] | Commercial Real Estate [Member] | 30-59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		324		125
Commercial [Member] | Commercial Real Estate [Member] | 30-59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	324		125
Commercial [Member] | Commercial Real Estate [Member] | 30-59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0		0
Commercial [Member] | Commercial Real Estate [Member] | 60-89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0		77
Commercial [Member] | Commercial Real Estate [Member] | 60-89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	0		77
Commercial [Member] | Commercial Real Estate [Member] | 60-89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0		0
Commercial [Member] | Commercial Real Estate [Member] | 90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0		279
Commercial [Member] | Commercial Real Estate [Member] | 90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	0		279
Commercial [Member] | Commercial Real Estate [Member] | 90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0		0
Commercial [Member] | Other [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		80		80
Current		51,958		44,971
Total loans		52,038		45,051
Commercial [Member] | Other [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	80		80
Current	[1]	51,593		44,852
Total loans	[1]	51,673	[2]	44,932
Commercial [Member] | Other [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0		0
Current		365		119
Total loans		365		119
Commercial [Member] | Other [Member] | 30-59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0		0
Commercial [Member] | Other [Member] | 30-59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	0		0
Commercial [Member] | Other [Member] | 30-59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0		0
Commercial [Member] | Other [Member] | 60-89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0		0
Commercial [Member] | Other [Member] | 60-89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	0		0
Commercial [Member] | Other [Member] | 60-89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0		0
Commercial [Member] | Other [Member] | 90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		80		80
Commercial [Member] | Other [Member] | 90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	80		80
Commercial [Member] | Other [Member] | 90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0		0
Real Estate Mortgage - 1 to 4 Family [Member]
Aging of the recorded investment in past due loans [Abstract]
Total loans		4,043,481		4,022,361
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		14,982		14,666
Current		3,723,065		3,691,030
Total loans		3,738,047		3,705,696
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	12,853		13,129
Current	[1]	2,602,725		2,593,652
Total loans	[1]	2,615,578		2,606,781
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		2,129		1,537
Current		1,120,340		1,097,378
Total loans		1,122,469		1,098,915
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 30-59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		2,491		1,585
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 30-59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	1,439		1,220
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 30-59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1,052		365
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 60-89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		444		1,499
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 60-89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	281		982
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 60-89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		163		517
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		12,047		11,582
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	11,133		10,927
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		914		655
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		244		216
Current		69,546		74,255
Total loans		69,790		74,471
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	197		169
Current	[1]	55,272		59,231
Total loans	[1]	55,469		59,400
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		47		47
Current		14,274		15,024
Total loans		14,321		15,071
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 30-59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		147		120
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 30-59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	147		120
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 30-59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0		0
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 60-89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1		1
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 60-89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	0		1
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 60-89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1		0
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		96		95
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	50		48
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		46		47
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		2,258		2,018
Current		233,386		240,176
Total loans		235,644		242,194
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	2,037		2,018
Current	[1]	183,200		191,636
Total loans	[1]	185,237		193,654
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		221		0
Current		50,186		48,540
Total loans		50,407		48,540
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 30-59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		413		401
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 30-59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	413		401
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 30-59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0		0
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 60-89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		361		344
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 60-89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	140		344
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 60-89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		221		0
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1,484		1,273
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	1,484		1,273
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0		0
Installment [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		25		63
Current		8,645		9,554
Total loans		8,670		9,617
Installment [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	6		46
Current	[1]	7,066		7,764
Total loans	[1]	7,072		7,810
Installment [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		19		17
Current		1,579		1,790
Total loans		1,598		1,807
Installment [Member] | 30-59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		25		10
Installment [Member] | 30-59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	6		3
Installment [Member] | 30-59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		19		7
Installment [Member] | 60-89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0		10
Installment [Member] | 60-89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	0		0
Installment [Member] | 60-89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0		10
Installment [Member] | 90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0		43
Installment [Member] | 90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	0		43
Installment [Member] | 90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		$ 0		$ 0

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

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