Stock Purchase Warrants (Details)		12 Months Ended
	Sep. 09, 2016 holder $ / shares shares	Dec. 31, 2016 $ / shares	Dec. 31, 2015 $ / shares	Dec. 21, 2016 $ / shares	Sep. 30, 2016 $ / shares shares	Jul. 09, 2014 $ / shares shares	Aug. 31, 2013 $ / shares shares
Assumptions used in calculating the estimated fair value of the warrants
Closing stock price (in dollars per share)				$ 2.75
August 2013 warrants
Stock Purchase Warrants
Exercise price per share (in dollars per share)						$ 4.80	$ 4.80
Total shares issuable on exercise (in shares) | shares						362,500	724,950
Assumptions used in calculating the estimated fair value of the warrants
Closing stock price (in dollars per share)	$ 2.20	$ 3	$ 2.58
Expected dividend rate	0.00%	0.00%	0.00%
Expected stock price volatility	89.80%	97.90%	91.40%
Risk-free interest rate	1.40%	1.03%	1.31%
Expected life	6 years	1 year 7 months 12 days	2 years 7 months 17 days
September 2022 Warrants
Stock Purchase Warrants
Exercise price per share (in dollars per share)					$ 2.48
Total shares issuable on exercise (in shares) | shares					117,074
September 2016 Warrants
Stock Purchase Warrants
Warrants issued (in shares) | shares	117,074
Number of holders (in holders) | holder	2