Consolidated Statements of Stockholders' Equity (Deficit) (Unaudited) (Parentheticals) - shares	3 Months Ended
Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020
Common Stock [Member]
Employee stock purchase plan sales, shares (in shares)		193,000		110,000
Exercise of stock options, shares (in shares)	1,056,000	593,000	193,000
Issuance of common stock, shares (in shares)			22,044,000
Warrants issued (in shares)			3,511,000

Number of share options (or share units) exercised during the current period.

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