Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets
Allowance for doubtful accounts receivable, current	$ 0	$ 26
Stockholders equity
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	25,000	25,000
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	150,000	150,000
Common stock, shares issued	100,105	78,597
Common stock, shares outstanding	100,105	78,597