Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Consolidated Statements of Financial Condition [Abstract]
Available-for-sale Securities, Amortized Cost	$ 102,345	$ 113,555
Held-to-maturity Securities, Fair Value	$ 60,303	$ 62,420
Common stock par value per share	$ 1.00	$ 1.00
Common stock, shares authorized	20,000,000	20,000,000
Common stock, shares, issued	4,375,645	4,362,939
Common stock, shares, outstanding	4,311,860	4,286,117
Treasury stock, shares	63,785	76,822