Loans and Allowance for Loan Losses (Details) - USD ($) $ in Thousands		Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		$ 3,578,282		$ 3,430,586
Less: Allowance for loan losses		44,082	$ 44,162	43,890	$ 43,950	$ 44,064	$ 44,762
Net loans		3,534,200		3,386,696
New York and Other States [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net	[1]	2,763,629		2,692,335
Florida [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		814,653		738,251
Real Estate Construction Loans [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		27,600		24,800
Residential Borrowers [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		17,200		16,300
Commercial Borrowers Residential Purpose [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		10,400		8,500
Commercial [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		187,281		191,194
Less: Allowance for loan losses		4,620	4,596	4,929	5,198	5,046	4,491
Commercial [Member] | New York and Other States [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		173,982		178,905
Commercial [Member] | Florida [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		13,299		12,289
Commercial [Member] | Commercial Real Estate [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		165,208		163,609
Commercial [Member] | Commercial Real Estate [Member] | New York and Other States [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net	[1]	152,228		151,366
Commercial [Member] | Commercial Real Estate [Member] | Florida [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		12,980		12,243
Commercial [Member] | Other [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		22,073		27,585
Commercial [Member] | Other [Member] | New York and Other States [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net	[1]	21,754		27,539
Commercial [Member] | Other [Member] | Florida [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		319		46
Real Estate Mortgage - 1 to 4 Family [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		3,382,723		3,230,574
Less: Allowance for loan losses		38,736	38,871	38,231	38,067	38,589	39,753
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		2,993,849		2,824,087
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | New York and Other States [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net	[1]	2,251,152		2,158,904
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | Florida [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		742,697		665,183
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		77,121		71,646
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | New York and Other States [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net	[1]	64,556		60,892
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | Florida [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		12,565		10,754
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		311,753		334,841
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | New York and Other States [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net	[1]	267,143		286,586
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | Florida [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		44,610		48,255
Installment [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		8,278		8,818
Less: Allowance for loan losses		726	$ 695	730	$ 685	$ 429	$ 518
Installment [Member] | New York and Other States [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net	[1]	6,796		7,048
Installment [Member] | Florida [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		$ 1,482		$ 1,770

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