Balance Sheets (Parenthetical) (USD $)	Sep. 28, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Trade accounts receivable allowance for doubtful accounts	$ 289,000	$ 288,000
Preferred stock - par value (in dollars per share)	$ 0.10	$ 0.10
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	18,941,544	18,851,579
Treasury stock shares	1,544,534	1,372,757