Convertible Preferred Stock and Stock Warrants (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Outstanding shares of preferred stock (in shares)	0	0
Issued shares of preferred stock (in shares)	2,450,339	0
Stock warrants exercised (in shares)			1,277,250
Exercise price of the exercisable warrants (in dollars per share)			$ 1.21
Cash proceeds from exercise of warrants	$ 0	$ 0	$ 1,545
Convertible Preferred Stock
Class of Stock [Line Items]
Issued shares of preferred stock (in shares)	0