CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Preferred stock authorized (in shares)	33,333	33,333
Common stock par value (in USD per share)	$ 0.001	$ 0.001
Common stock authorized (in shares)	101,500,000	81,500,000
Common stock issued (in shares)	57,986,075	42,969,494
Common stock outstanding (in shares)	57,986,075	42,969,494
Series O Preferred Stock
Preferred stock par value (in USD per share)	$ 0.001	$ 0.001
Preferred stock issued (in shares)	12,575	0
Preferred stock outstanding (in shares)	12,575	0
Preferred stock liquidation preference	$ 25,150	$ 0
Series N Preferred Stock
Preferred stock par value (in USD per share)	$ 0.001	$ 0.001
Preferred stock issued (in shares)	0	575
Preferred stock outstanding (in shares)	0	575
Preferred stock liquidation preference	$ 0	$ 1,150