Consolidated Balance Sheets (Parentheticals) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Trade, allowance	$ 348,000	$ 348,000
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	2,000,000	2,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	192,000,000	192,000,000
Common stock, shares issued (in shares)	83,034,404	82,705,005
Common stock, shares outstanding (in shares)	83,034,404	82,705,005