Condensed Balance Sheets (Parenthetical) - $ / shares shares in Thousands	Jun. 30, 2018	Dec. 31, 2017
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	150,000	900,000
Common stock, shares issued	33,155	5,342
Common stock, shares outstanding	33,155	5,342
Series A-1
Convertible preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Convertible preferred stock, shares authorized	0	151,773
Convertible preferred stock, shares issued	0	151,773
Convertible preferred stock, shares outstanding	0	151,773
Series A-2
Convertible preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Convertible preferred stock, shares authorized	0	173,453
Convertible preferred stock, shares issued	0	173,453
Convertible preferred stock, shares outstanding	0	173,453
Series B
Convertible preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Convertible preferred stock, shares authorized	0	234,955
Convertible preferred stock, shares issued	0	234,955
Convertible preferred stock, shares outstanding	0	234,955