Consolidated Balance Sheets (Parentheticals) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	85,000,000	85,000,000
Common stock, shares issued (in shares)	64,171,435	49,410,176
Common stock, shares outstanding (in shares)	64,138,102	49,376,843
Treasury stock, at cost, shares (in shares)	33,333	33,333