Consolidated Balance Sheets (Parentheticals)	12 Months Ended
	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares
Common stock, par value (in dollars per share) | $ / shares	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	25,000,000	25,000,000
Common stock, shares issued (in shares)	20,547,668	18,228,887
Common stock, shares outstanding (in shares)	20,547,668	18,228,887
Common stock, reverse stock split 4-to-1	4	4
Accounts receivable, allowance for doubtful accounts | $	$ 612,434	$ 971,772
Preferred stock, par value (in dollars per share) | $ / shares	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	2,500,000	2,500,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0