Common Stock Warrant Exercises, Stock Option Exercises and Employee Stock Purchases (Details) - USD ($) shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Common Stock Warrant Exercises, Stock Option Exercises and Employee Stock Purchases
Warrant exercises, Shares		136
Stock option exercises, Shares		332
Employee stock purchases, Shares	79	19
Total, Shares	79	487
Warrant exercises, Proceeds		$ 503
Stock option exercises, Proceeds		(431)
Employee stock purchases, Proceeds	$ (111)	(53)
Total, Proceeds	$ 111	$ 987