Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Consolidated Statements of Financial Condition [Abstract]
Available-for-sale Securities, Amortized Cost	$ 106,450	$ 113,555
Held-to-maturity Securities, Fair Value	$ 60,815	$ 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	4,370,185	4,362,939
Common stock, shares, outstanding	4,301,898	4,286,117
Treasury stock, shares	68,287	76,822