Consolidated Statements of Stockholders' Equity (Deficit) (Parentheticals) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
January 2019 Public Offering [Member]
Common stock issued, transaction costs		$ 739
May 2019 Public Offering [Member]
Common stock issued, transaction costs		$ 1,683
ATM [Member]
Common stock issued, transaction costs	$ 216