Consolidated Statements Stockholders' Equity (Deficit) (Unaudited) (Parentheticals) - Common Stock [Member] - shares shares in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Exercise of stock options, shares (in shares)	160	242
Employee stock purchase plan sales, shares (in shares)	47	49

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

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Period Type:	duration