Loans and Allowance for Loan Losses, Impaired Receivables (Details) - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2019	Dec. 31, 2018
Impaired loans by loans class [Abstract]
Recorded Investment		$ 20,927	$ 22,288
Unpaid Principal Balance		21,518	23,309
Related Allowance		0	0
Average Recorded Investment		21,290	23,161
New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	[1]	18,027	19,546
Unpaid Principal Balance	[1]	18,618	20,461
Related Allowance	[1]	0	0
Average Recorded Investment	[1]	18,646	20,237
Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		2,900	2,742
Unpaid Principal Balance		2,900	2,848
Related Allowance		0	0
Average Recorded Investment		2,644	2,924
Commercial [Member] | Commercial Real Estate [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		1,453	1,386
Unpaid Principal Balance		1,595	1,556
Related Allowance		0	0
Average Recorded Investment		1,483	1,560
Commercial [Member] | Commercial Real Estate [Member] | New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	[1]	1,346	1,274
Unpaid Principal Balance	[1]	1,488	1,444
Related Allowance	[1]	0	0
Average Recorded Investment	[1]	1,373	1,503
Commercial [Member] | Commercial Real Estate [Member] | Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		107	112
Unpaid Principal Balance		107	112
Related Allowance		0	0
Average Recorded Investment		110	57
Commercial [Member] | Other [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		68	38
Unpaid Principal Balance		68	88
Related Allowance		0	0
Average Recorded Investment		45	123
Commercial [Member] | Other [Member] | New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	[1]	68	38
Unpaid Principal Balance	[1]	68	88
Related Allowance	[1]	0	0
Average Recorded Investment	[1]	45	123
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	0
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		16,500	17,503
Unpaid Principal Balance		16,788	18,060
Related Allowance		0	0
Average Recorded Investment		16,767	18,032
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]	13,995	15,210
Unpaid Principal Balance	[1]	14,283	15,661
Related Allowance	[1]	0	0
Average Recorded Investment	[1]	14,556	15,577
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		2,505	2,293
Unpaid Principal Balance		2,505	2,399
Related Allowance		0	0
Average Recorded Investment		2,211	2,455
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		278	336
Unpaid Principal Balance		299	356
Related Allowance		0	0
Average Recorded Investment		317	348
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]	238	252
Unpaid Principal Balance	[1]	259	272
Related Allowance	[1]	0	0
Average Recorded Investment	[1]	245	262
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		40	84
Unpaid Principal Balance		40	84
Related Allowance		0	0
Average Recorded Investment		72	86
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		2,628	3,025
Unpaid Principal Balance		2,768	3,249
Related Allowance		0	0
Average Recorded Investment		2,678	3,098
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]	2,380	2,772
Unpaid Principal Balance	[1]	2,520	2,996
Related Allowance	[1]	0	0
Average Recorded Investment	[1]	2,427	2,772
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment		248	253
Unpaid Principal Balance		248	253
Related Allowance		0	0
Average Recorded Investment		$ 251	$ 326

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