Balance Sheets (Parenthetical) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Allowance for doubtful accounts (in dollars)	$ 198,623	$ 165,840
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	25,000,000	25,000,000
Common stock, shares issued	4,656,734	4,656,734
Common stock, shares outstanding	4,506,788	4,528,669
Treasury stock, shares	149,946	128,065