Loans and Allowance for Loan Losses, Past Due (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
		Mar. 31, 2019	Dec. 31, 2018
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		$ 22,934	$ 23,269
Current		3,838,219	3,850,827
Total loans		3,861,153	3,874,096
Loans that are 90 days past due and still accruing interest		$ 0	$ 0
Number of days past due		90 days	90 days
New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	$ 21,358	$ 21,550
Current	[1]	2,911,758	2,926,519
Total loans	[1]	2,933,116	2,948,069
Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1,576	1,719
Current		926,461	924,308
Total loans		928,037	926,027
30-59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		4,621	5,158
30-59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	3,893	4,639
30-59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		728	519
60-89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1,422	1,783
60-89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	1,195	1,369
60-89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		227	414
90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		16,891	16,328
90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	16,270	15,542
90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		621	786
Commercial [Member]
Aging of the recorded investment in past due loans [Abstract]
Total loans		190,347	196,146
Commercial [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total loans	[1]	174,714	180,608
Commercial [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total loans		15,633	15,538
Commercial [Member] | Commercial Real Estate [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		661	568
Current		167,456	170,985
Total loans		168,117	171,553
Commercial [Member] | Commercial Real Estate [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	661	568
Current	[1]	152,070	155,710
Total loans	[1]	152,731	156,278
Commercial [Member] | Commercial Real Estate [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Current		15,386	15,275
Total loans		15,386	15,275
Commercial [Member] | Commercial Real Estate [Member] | 30-59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		96	198
Commercial [Member] | Commercial Real Estate [Member] | 30-59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	96	198
Commercial [Member] | Commercial Real Estate [Member] | 30-59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Commercial [Member] | Commercial Real Estate [Member] | 60-89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Commercial [Member] | Commercial Real Estate [Member] | 60-89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	0	0
Commercial [Member] | Commercial Real Estate [Member] | 60-89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Commercial [Member] | Commercial Real Estate [Member] | 90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		565	370
Commercial [Member] | Commercial Real Estate [Member] | 90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	565	370
Commercial [Member] | Commercial Real Estate [Member] | 90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Commercial [Member] | Other [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Current		22,230	24,593
Total loans		22,230	24,593
Commercial [Member] | Other [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	0	0
Current	[1]	21,983	24,330
Total loans	[1]	21,983	24,330
Commercial [Member] | Other [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Current		247	263
Total loans		247	263
Commercial [Member] | Other [Member] | 30-59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Commercial [Member] | Other [Member] | 30-59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	0	0
Commercial [Member] | Other [Member] | 30-59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Commercial [Member] | Other [Member] | 60-89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Commercial [Member] | Other [Member] | 60-89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	0	0
Commercial [Member] | Other [Member] | 60-89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Commercial [Member] | Other [Member] | 90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Commercial [Member] | Other [Member] | 90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	0	0
Commercial [Member] | Other [Member] | 90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Real Estate Mortgage - 1 to 4 Family [Member]
Aging of the recorded investment in past due loans [Abstract]
Total loans		3,658,227	3,666,248
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		18,381	18,986
Current		3,267,795	3,268,891
Total loans		3,286,176	3,287,877
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	17,049	17,441
Current	[1]	2,421,683	2,425,270
Total loans	[1]	2,438,732	2,442,711
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1,332	1,545
Current		846,112	843,621
Total loans		847,444	845,166
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 30-59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		3,401	3,693
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 30-59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	2,798	3,276
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 30-59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		603	417
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 60-89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		938	1,305
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 60-89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	780	898
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 60-89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		158	407
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		14,042	13,988
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	13,471	13,267
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		571	721
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		302	514
Current		89,715	88,317
Total loans		90,017	88,831
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	252	464
Current	[1]	71,501	71,059
Total loans	[1]	71,753	71,523
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		50	50
Current		18,214	17,258
Total loans		18,264	17,308
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 30-59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		16	208
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 30-59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	16	158
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 30-59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	50
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 60-89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		77	94
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 60-89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	27	94
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 60-89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		50	0
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		209	212
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	209	212
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		3,423	3,092
Current		278,611	286,448
Total loans		282,034	289,540
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	3,253	3,002
Current	[1]	234,621	240,763
Total loans	[1]	237,874	243,765
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		170	90
Current		43,990	45,685
Total loans		44,160	45,775
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 30-59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1,033	1,003
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 30-59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	913	963
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 30-59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		120	40
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 60-89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		341	348
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 60-89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	341	348
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 60-89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		2,049	1,741
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	1,999	1,691
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		50	50
Installment [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		167	109
Current		12,412	11,593
Total loans		12,579	11,702
Installment [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	143	75
Current	[1]	9,900	9,387
Total loans	[1]	10,043	9,462
Installment [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		24	34
Current		2,512	2,206
Total loans		2,536	2,240
Installment [Member] | 30-59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		75	56
Installment [Member] | 30-59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	70	44
Installment [Member] | 30-59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		5	12
Installment [Member] | 60-89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		66	36
Installment [Member] | 60-89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	47	29
Installment [Member] | 60-89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		19	7
Installment [Member] | 90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		26	17
Installment [Member] | 90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due	[1]	26	2
Installment [Member] | 90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		$ 0	$ 15

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