CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized	250,000,000	250,000,000
Common stock, issued	37,728,000	37,341,000
Common stock, outstanding	37,728,000	37,341,000
Preferred stock, Series A
Preferred stock, authorized	200,000	200,000
Preferred stock, Undesignated series
Preferred stock, authorized	59,800,000	59,800,000