Fair Values Measurements and Fair Values of Financial Instruments (Carrying Values and Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	$ 91,613	$ 119,335
Equity securities	2,500	7,672
Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	550,353	195,264
Interest-earning time deposits	735	735
Debt securities available for sale	91,613	119,335
Equity securities	2,500	7,672
Loans held for sale	917	1,153
Loans receivable, net	2,178,407	2,278,492
FHLB of New York stock, at cost	13,821	13,405
Accrued interest receivable	8,318	8,378
Deposits	2,362,063	2,180,724
Debt	245,800	245,800
Subordinated debentures	36,810	36,577
Accrued interest payable	2,708	2,561
Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	550,353	195,264
Interest-earning time deposits	735	735
Debt securities available for sale	91,613	119,335
Equity securities	2,500	7,672
Loans held for sale	917	1,153
Loans receivable, net	2,199,497	2,245,150
FHLB of New York stock, at cost	13,821	13,405
Accrued interest receivable	8,318	8,378
Deposits	2,375,089	2,189,404
Debt	247,176	244,049
Subordinated debentures	36,947	36,316
Accrued interest payable	2,708	2,561
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	550,353	195,264
Equity securities	2,500	7,672
Deposits	1,231,658	1,075,539
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest-earning time deposits	735	735
Debt securities available for sale	91,613	119,335
Loans held for sale	917	1,153
FHLB of New York stock, at cost	13,821	13,405
Accrued interest receivable	8,318	8,378
Deposits	1,143,431	1,113,865
Debt	247,176	244,049
Subordinated debentures	36,947	36,316
Accrued interest payable	2,708	2,561
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans receivable, net	$ 2,199,497	$ 2,245,150