Loans and Allowance for Loan Losses, Recorded Investment in Loans by Loan Class (Details) - USD ($) $ in Thousands		Sep. 30, 2021		Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Loans and Leases Receivable [Abstract]
Total loans, net		$ 4,396,729			$ 4,244,470
Less: Allowance for loan losses		47,350		$ 50,155	49,595	$ 49,123	$ 48,144	$ 44,317
Net loans		4,349,379			4,194,875
New York and Other States [Member]
Loans and Leases Receivable [Abstract]
Total loans, net	[1]	3,116,615			3,061,352
Florida [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		1,280,114			1,183,118
Real Estate Construction Loans [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		37,700			24,700
Residential Borrowers [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		21,900			10,500
Commercial Borrowers Residential Purpose [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		15,800			14,200
Commercial [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		204,679			212,492
Less: Allowance for loan losses		3,253		4,106	4,140	4,267	4,366	3,999
Commercial [Member] | New York and Other States [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		183,635	[2]		193,707
Commercial [Member] | Florida [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		21,044			18,785
Commercial [Member] | Commercial Real Estate [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		168,069			167,441
Commercial [Member] | Commercial Real Estate [Member] | New York and Other States [Member]
Loans and Leases Receivable [Abstract]
Total loans, net	[1]	147,557	[2]		148,775
Commercial [Member] | Commercial Real Estate [Member] | Florida [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		20,512			18,666
Commercial [Member] | Other [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		36,610			45,051
Commercial [Member] | Other [Member] | New York and Other States [Member]
Loans and Leases Receivable [Abstract]
Total loans, net	[1]	36,078	[2]		44,932
Commercial [Member] | Other [Member] | Florida [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		532			119
Commercial [Member] | PPP Loans [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		20,500			28,900
Real Estate Mortgage - 1 to 4 Family [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		4,182,599			4,022,361
Less: Allowance for loan losses		43,653		45,617	44,950	44,323	43,274	39,748
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		3,887,956			3,705,696
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | New York and Other States [Member]
Loans and Leases Receivable [Abstract]
Total loans, net	[1]	2,698,870			2,606,781
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | Florida [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		1,189,086			1,098,915
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		63,329			74,471
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | New York and Other States [Member]
Loans and Leases Receivable [Abstract]
Total loans, net	[1]	49,492			59,400
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | Florida [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		13,837			15,071
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		231,314			242,194
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | New York and Other States [Member]
Loans and Leases Receivable [Abstract]
Total loans, net	[1]	177,240			193,654
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | Florida [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		54,074			48,540
Installment [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		9,451			9,617
Less: Allowance for loan losses		444		$ 432	505	$ 533	$ 504	$ 570
Installment [Member] | New York and Other States [Member]
Loans and Leases Receivable [Abstract]
Total loans, net	[1]	7,378			7,810
Installment [Member] | Florida [Member]
Loans and Leases Receivable [Abstract]
Total loans, net		$ 2,073			$ 1,807

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

[2] Includes New York, New Jersey and Massachusetts.