CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2017	Dec. 31, 2016
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	75,000,000	40,000,000
Common stock, shares issued (in shares)	32,975,174	31,002,832
Common stock, shares outstanding (in shares)	32,832,095	30,859,753
Series B Preferred Stock
Stockholders' equity:
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	3,588,139	3,588,139
Preferred stock, shares issued (in shares)	0	975,639
Preferred stock, shares outstanding (in shares)	0	975,639