CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	150,000,000	150,000,000
Common stock shares issued on exercise of options (in shares)	29,943,086	4,304,425
Common stock, shares outstanding (in shares)	29,943,086	4,304,425
Series C Convertible Preferred Stock [Member]
Stockholders' equity:
Preferred stock, par value (in dollars per share)	$ 0.10	$ 0.10
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	9,968	36,182
Preferred stock, shares outstanding (in shares)	9,968	36,182

Face amount or stated value per share of common stock.

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