CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (Unaudited) - $ / shares shares in Thousands	Jun. 30, 2019	Dec. 31, 2018	[1]
Stockholders' equity
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	142,857	142,857
Common stock, issued (in shares)	6,623	5,938
Common stock, outstanding (in shares)	6,623	5,938

[1] Derived from the Company's audited consolidated financial statements as of December 31, 2018.