Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	183,123,000	180,536,000
Common stock, shares outstanding	183,123,000	180,536,000
Series A Convertible Preferred Stock
Convertible preferred stock, par value	$ 0.0001	$ 0.0001
Convertible preferred stock, shares authorized	88,000	88,000
Convertible preferred stock, shares issued	88,000	88,000
Convertible preferred stock, shares outstanding	88,000	88,000
Convertible preferred stock, liquidation value	$ 87,500	$ 87,500