Consolidated Balance Sheets (Parentheticals) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Preferred stock, par value (in dollars per share)	$ 0.005	$ 0.005
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.005	$ 0.005
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	54,389,829	51,197,989
Common stock, shares outstanding (in shares)	54,286,229	51,094,389
Treasury stock, shares (in shares)	103,600	103,600