Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2015	Dec. 31, 2014
Statement Of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized	8,000,000	8,000,000
Common stock, shares issued	3,261,148	3,261,148
Treasury stock, shares	206,114	234,114