Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Consolidated Statements of Financial Condition [Abstract]
Available-for-sale Securities, Amortized Cost	$ 109,262	$ 116,830
Held-to-maturity Securities, Fair Value	$ 67,229	$ 66,124
Common Stock, Par or Stated Value Per Share	$ 1.00	$ 1.00
Common Stock, Shares Authorized	20,000,000	20,000,000
Common Stock, Shares, Issued	4,343,616	4,334,352
Common Stock, Shares, Outstanding	4,262,721	4,240,778
Treasury Stock, Shares	80,895	93,574