Loans and Allowance for Loan Losses, Allowance for Loan Losses (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Allowance for loan losses by portfolio segment [Roll Forward]
Balance at beginning of period		$ 44,365	$ 44,503	$ 44,766	$ 44,170
Loans charged off [Abstract]
Total loan charge offs		192	172	934	660
Recoveries of loans previously charged off [Abstract]
Total recoveries		156	105	538	326
Net loans (recoveries) charged off		36	67	396	334
(Recoveries) provision for loan losses		0	300	(41)	900
Balance at end of period		44,329	44,736	44,329	44,736
New York and Other States [Member]
Loans charged off [Abstract]
Total loan charge offs	[1]	176	163	858	645
Recoveries of loans previously charged off [Abstract]
Total recoveries	[1]	156	104	503	322
Florida [Member]
Loans charged off [Abstract]
Total loan charge offs		16	9	76	15
Recoveries of loans previously charged off [Abstract]
Total recoveries		0	1	35	4
Commercial [Member]
Allowance for loan losses by portfolio segment [Roll Forward]
Balance at beginning of period		3,913	4,195	4,048	4,324
Loans charged off [Abstract]
Total loan charge offs		13	0	20	0
Recoveries of loans previously charged off [Abstract]
Total recoveries		41	2	45	9
Net loans (recoveries) charged off		(28)	(2)	(25)	(9)
(Recoveries) provision for loan losses		(70)	(65)	(202)	(201)
Balance at end of period		3,871	4,132	3,871	4,132
Commercial [Member] | New York and Other States [Member]
Loans charged off [Abstract]
Total loan charge offs	[1]	13	0	20	0
Recoveries of loans previously charged off [Abstract]
Total recoveries	[1]	41	2	45	9
Commercial [Member] | Florida [Member]
Loans charged off [Abstract]
Total loan charge offs		0	0	0	0
Recoveries of loans previously charged off [Abstract]
Total recoveries		0	0	0	0
Real Estate Mortgage - 1 to 4 Family [Member]
Allowance for loan losses by portfolio segment [Roll Forward]
Balance at beginning of period		39,963	39,471	39,772	39,077
Loans charged off [Abstract]
Total loan charge offs		147	94	773	464
Recoveries of loans previously charged off [Abstract]
Total recoveries		108	97	476	289
Net loans (recoveries) charged off		39	(3)	297	175
(Recoveries) provision for loan losses		(18)	227	431	799
Balance at end of period		39,906	39,701	39,906	39,701
Real Estate Mortgage - 1 to 4 Family [Member] | New York and Other States [Member]
Loans charged off [Abstract]
Total loan charge offs	[1]	147	94	744	464
Recoveries of loans previously charged off [Abstract]
Total recoveries	[1]	108	97	441	289
Real Estate Mortgage - 1 to 4 Family [Member] | Florida [Member]
Loans charged off [Abstract]
Total loan charge offs		0	0	29	0
Recoveries of loans previously charged off [Abstract]
Total recoveries		0	0	35	0
Installment [Member]
Allowance for loan losses by portfolio segment [Roll Forward]
Balance at beginning of period		489	837	946	769
Loans charged off [Abstract]
Total loan charge offs		32	78	141	196
Recoveries of loans previously charged off [Abstract]
Total recoveries		7	6	17	28
Net loans (recoveries) charged off		25	72	124	168
(Recoveries) provision for loan losses		88	138	(270)	302
Balance at end of period		552	903	552	903
Installment [Member] | New York and Other States [Member]
Loans charged off [Abstract]
Total loan charge offs	[1]	16	69	94	181
Recoveries of loans previously charged off [Abstract]
Total recoveries	[1]	7	5	17	24
Installment [Member] | Florida [Member]
Loans charged off [Abstract]
Total loan charge offs		16	9	47	15
Recoveries of loans previously charged off [Abstract]
Total recoveries		$ 0	$ 1	$ 0	$ 4

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