CONSOLIDATED BALANCE SHEET (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Preferred stock, shares authorized (in shares)	3,000,000	3,000,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 8.33	$ 8.33
Common stock, shares authorized (in shares)	15,000,000	15,000,000
Common stock, shares issued (in shares)	5,009,339	5,007,109
Common stock, shares outstanding (in shares)	4,689,189	4,734,657
Treasury stock, shares (in shares)	320,150	272,452