Loans and Allowance for Loan Losses, Impaired Receivables (Details) - USD ($) $ in Thousands		9 Months Ended		12 Months Ended
		Sep. 30, 2021		Dec. 31, 2020
Impaired loans by loans class [Abstract]
Recorded Investment		$ 19,813		$ 21,581
Unpaid Principal Balance		20,351		22,253
Related Allowance		0		0
Average Recorded Investment		20,744		20,814
New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	[1]	16,940		18,331
Unpaid Principal Balance	[1]	17,478		19,003
Related Allowance	[1]	0		0
Average Recorded Investment	[1]	17,815		17,892
Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		2,873		3,250
Unpaid Principal Balance		2,873		3,250
Related Allowance		0		0
Average Recorded Investment		2,929		2,922
Commercial [Member] | Commercial Real Estate [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		481		917
Unpaid Principal Balance		573		1,041
Related Allowance		0		0
Average Recorded Investment		1,252		1,291
Commercial [Member] | Commercial Real Estate [Member] | New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	[1]	388		819
Unpaid Principal Balance	[1]	480		943
Related Allowance	[1]	0		0
Average Recorded Investment	[1]	1,147		1,186
Commercial [Member] | Commercial Real Estate [Member] | Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		93		98
Unpaid Principal Balance		93	[1]	98
Related Allowance		0		0
Average Recorded Investment		105		105
Commercial [Member] | Other [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		40		111
Unpaid Principal Balance		40		111
Related Allowance		0		0
Average Recorded Investment		108		103
Commercial [Member] | Other [Member] | New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	[1]	40		111
Unpaid Principal Balance	[1]	40		111
Related Allowance	[1]	0		0
Average Recorded Investment	[1]	108		103
Commercial [Member] | Other [Member] | Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		0		0
Unpaid Principal Balance		0	[1]	0
Related Allowance		0		0
Average Recorded Investment		0		0
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		16,858		17,932
Unpaid Principal Balance		17,164		18,319
Related Allowance		0		0
Average Recorded Investment		16,633		16,665
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	[1]	14,261		15,024
Unpaid Principal Balance	[1]	14,567		15,411
Related Allowance	[1]	0		0
Average Recorded Investment	[1]	14,070		14,110
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		2,597		2,908
Unpaid Principal Balance		2,597		2,908
Related Allowance		0		0
Average Recorded Investment		2,563		2,555
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		199		219
Unpaid Principal Balance		199		240
Related Allowance		0		0
Average Recorded Investment		250		251
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	[1]	199		219
Unpaid Principal Balance	[1]	199		240
Related Allowance	[1]	0		0
Average Recorded Investment	[1]	235		235
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		0		0
Unpaid Principal Balance		0		0
Related Allowance		0		0
Average Recorded Investment		15		16
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		2,235		2,402
Unpaid Principal Balance		2,375		2,542
Related Allowance		0		0
Average Recorded Investment		2,501		2,504
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	[1]	2,052		2,158
Unpaid Principal Balance	[1]	2,192		2,298
Related Allowance	[1]	0		0
Average Recorded Investment	[1]	2,255		2,258
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		183		244
Unpaid Principal Balance		183		244
Related Allowance		0		0
Average Recorded Investment		$ 246		$ 246

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