Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Preferred stock, no par value (in dollars per share)
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares outstanding (in shares)	0	0
Common stock, no par value (in dollars per share)
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares issued (in shares)	27,908,000	23,214,000
Common stock, shares outstanding (in shares)	27,908,000	23,214,000