BALANCE SHEETS (Parenthetical) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Allowance for doubtful accounts (in dollars)	$ 165,840	$ 181,473
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized	25,000,000	25,000,000
Common stock, issued	4,656,734	4,656,734
Common stock, outstanding	4,528,669	4,511,965
Treasury stock	128,065	144,769