Loans and Allowance for Loan Losses, Impaired Receivables (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Impaired loans by loans class [Abstract]
Recorded Investment	$ 24,554	$ 24,025
Unpaid Principal Balance	26,229	26,201
Related Allowance	0	0
Average Recorded Investment	24,964	22,408
New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	21,594	21,361
Unpaid Principal Balance	23,163	23,374
Related Allowance	0	0
Average Recorded Investment	22,087	19,936
Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	2,960	2,664
Unpaid Principal Balance	3,066	2,827
Related Allowance	0	0
Average Recorded Investment	2,877	2,472
Commercial [Member] | Commercial Real Estate [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	2,869	2,418
Unpaid Principal Balance	3,916	3,470
Related Allowance	0	0
Average Recorded Investment	2,879	2,214
Commercial [Member] | Commercial Real Estate [Member] | New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	2,869	2,418
Unpaid Principal Balance	3,916	3,470
Related Allowance	0	0
Average Recorded Investment	2,879	2,214
Commercial [Member] | Commercial Real Estate [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
Commercial [Member] | Other [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	100	0
Unpaid Principal Balance	100	0
Related Allowance	0	0
Average Recorded Investment	100	0
Commercial [Member] | Other [Member] | New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	100	0
Unpaid Principal Balance	100	0
Related Allowance	0	0
Average Recorded Investment	100	0
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	18,378	18,684
Unpaid Principal Balance	18,792	19,539
Related Allowance	0	0
Average Recorded Investment	18,932	17,465
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	16,043	16,675
Unpaid Principal Balance	16,351	17,439
Related Allowance	0	0
Average Recorded Investment	16,715	15,665
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	2,335	2,009
Unpaid Principal Balance	2,441	2,100
Related Allowance	0	0
Average Recorded Investment	2,217	1,800
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	342	363
Unpaid Principal Balance	362	399
Related Allowance	0	0
Average Recorded Investment	358	332
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	252	269
Unpaid Principal Balance	272	305
Related Allowance	0	0
Average Recorded Investment	265	251
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	90	94
Unpaid Principal Balance	90	94
Related Allowance	0	0
Average Recorded Investment	92	81
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	2,865	2,560
Unpaid Principal Balance	3,059	2,793
Related Allowance	0	0
Average Recorded Investment	2,696	2,397
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	2,330	1,999
Unpaid Principal Balance	2,524	2,160
Related Allowance	0	0
Average Recorded Investment	2,128	1,806
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	535	561
Unpaid Principal Balance	535	633
Related Allowance	0	0
Average Recorded Investment	$ 568	$ 591