Loans and Allowance for Loan Losses, Impaired Receivables (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
		Mar. 31, 2020	Dec. 31, 2019
Impaired loans by loans class [Abstract]
Recorded Investment		$ 20,287	$ 20,976
Unpaid Principal Balance		20,964	21,578
Related Allowance		0	0
Average Recorded Investment		20,743	20,963
New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	[1]	17,324	18,141
Unpaid Principal Balance	[1]	18,001	18,743
Related Allowance	[1]	0	0
Average Recorded Investment	[1]	17,954	18,296
Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		2,963	2,835
Unpaid Principal Balance		2,963	2,835
Related Allowance		0	0
Average Recorded Investment		2,788	2,667
Commercial [Member] | Commercial Real Estate [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		970	1,322
Unpaid Principal Balance		1,110	1,464
Related Allowance		0	0
Average Recorded Investment		1,352	1,467
Commercial [Member] | Commercial Real Estate [Member] | New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	[1]	866	1,217
Unpaid Principal Balance	[1]	1,006	1,359
Related Allowance	[1]	0	0
Average Recorded Investment	[1]	1,245	1,385
Commercial [Member] | Commercial Real Estate [Member] | Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		104	105
Unpaid Principal Balance		104	105
Related Allowance		0	0
Average Recorded Investment		106	82
Commercial [Member] | Other [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		145	115
Unpaid Principal Balance		145	115
Related Allowance		0	0
Average Recorded Investment		91	64
Commercial [Member] | Other [Member] | New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	[1]	145	115
Unpaid Principal Balance	[1]	145	115
Related Allowance	[1]	0	0
Average Recorded Investment	[1]	91	38
Commercial [Member] | Other [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		0	26
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		16,487	16,900
Unpaid Principal Balance		16,864	17,200
Related Allowance		0	0
Average Recorded Investment		16,500	16,617
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]	13,872	14,414
Unpaid Principal Balance	[1]	14,249	14,714
Related Allowance	[1]	0	0
Average Recorded Investment	[1]	14,095	14,358
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		2,615	2,486
Unpaid Principal Balance		2,615	2,486
Related Allowance		0	0
Average Recorded Investment		2,405	2,259
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		232	235
Unpaid Principal Balance		252	255
Related Allowance		0	0
Average Recorded Investment		267	292
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]	232	235
Unpaid Principal Balance	[1]	252	255
Related Allowance	[1]	0	0
Average Recorded Investment	[1]	237	241
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		30	51
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		2,453	2,404
Unpaid Principal Balance		2,593	2,544
Related Allowance		0	0
Average Recorded Investment		2,533	2,523
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]	2,209	2,160
Unpaid Principal Balance	[1]	2,349	2,300
Related Allowance	[1]	0	0
Average Recorded Investment	[1]	2,286	2,274
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		244	244
Unpaid Principal Balance		244	244
Related Allowance		0	0
Average Recorded Investment		$ 247	$ 249

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