Stockholders' Equity (Details) $ / shares in Units, $ in Thousands									12 Months Ended
	Nov. 27, 2015 $ / shares shares	Nov. 23, 2015 USD ($) $ / shares shares	Jun. 02, 2015 USD ($) $ / shares shares	May. 19, 2015 USD ($)	Nov. 11, 2014 $ / shares shares	Nov. 04, 2014 USD ($) $ / shares shares	Apr. 04, 2014 USD ($) $ / shares $ / item shares	May. 15, 2012 USD ($)	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Oct. 07, 2015 $ / shares shares	Dec. 31, 2013 $ / shares
Subsidiary, Sale of Stock
Net proceeds | $									$ 7,115	$ 9,923
Warrants issued (in shares) | shares									2,957,138	1,448,964
Value of shares issued | $									$ 3,731	$ 7,380
Minimum
Subsidiary, Sale of Stock
Exercise price (in dollars per share)									$ 0.01	$ 1.25		$ 1.25
Maximum
Subsidiary, Sale of Stock
Exercise price (in dollars per share)									4.50	10.40		$ 10.40
Warrants Issued April 4, 2014, Liability
Subsidiary, Sale of Stock
Number of shares of stock into which each warrant may be converted (in shares) | shares							1
Warrants issued (in shares) | shares							812,000
Exercise price (in dollars per share)							$ 4.20		4.20	4.20
Number of shares into which warrants may be converted (in shares) | shares							812,000
Share price (in dollars per share)							$ 2.95		0.94	1.81
Net proceeds allocated to warrant liability | $							$ 1,500
Warrant component per unit sold (in shares) | shares							0.4
Price per unit | $ / item							3.40
Additional underwriting discounts and commissions and offering costs allocated to warrants | $							$ 200
Warrants Issued November 4, 2014, Liability
Subsidiary, Sale of Stock
Warrants issued (in shares) | shares						556,964
Exercise price (in dollars per share)										3.25
Share price (in dollars per share)										1.81
Net proceeds allocated to warrant liability | $						$ 1,300
Additional underwriting discounts and commissions and offering costs allocated to warrants | $						$ 100
Series A Warrants
Subsidiary, Sale of Stock
Warrants issued (in shares) | shares	771,000					388,393
Exercise price (in dollars per share)	$ 1.70					$ 3.25			1.70
Share price (in dollars per share)	$ 1.39					$ 3.04			0.94
Series B Warrants
Subsidiary, Sale of Stock
Warrants issued (in shares) | shares	1,686,138					168,571
Exercise price (in dollars per share)	$ 0.01					$ 0.01			0.01
Share price (in dollars per share)	$ 1.39					$ 3.04			$ 0.94
Warrants Issued June 2, 2015, Liability
Subsidiary, Sale of Stock
Gross proceeds | $			$ 5,100
Net proceeds | $			$ 4,500
Warrant component per unit sold (in shares) | shares			0.2
Exercise price (in dollars per share)			$ 2.65
Net proceeds allocated to warrant liability | $									$ 800
Additional underwriting discounts and commissions and offering costs allocated to warrants | $									100
Period before warrants become exercisable			6 months
Exercise period			5 years 6 months
Warrants Issued November 23, 2015, Liability
Subsidiary, Sale of Stock
Net proceeds | $		$ 2,600
Number of shares into which surrendered and cancelled warrants could have been converted | shares		856,393
Exercise price of warrants surrendered and cancelled (in dollars per share)		$ 3.19
Gross proceeds | $		$ 3,100
Gross proceeds allocated to warrant liability | $		3,400
Offering costs allocated to warrants issued | $		$ 400
Additional underwriting discounts and commissions and offering costs allocated to warrants | $									$ 400
Warrants Issued November 11, 2014, Liability
Subsidiary, Sale of Stock
Warrants issued (in shares) | shares					80,000
Exercise price (in dollars per share)					$ 1.75					1.75	$ 1.75
Number of shares into which warrants may be converted (in shares) | shares					80,000						75,000
Share price (in dollars per share)					$ 2.46				$ 0.94	$ 1.81
Exercise period					5 years
April 4, 2014, Offering
Subsidiary, Sale of Stock
Share component per unit sold (in shares) | shares							1
Shares issued | shares							2,030,000
Net proceeds allocated to equity | $							$ 4,600
April 4, 2014, Offering | Warrants Issued April 4, 2014, Liability
Subsidiary, Sale of Stock
Net proceeds | $							6,100
Gross proceeds | $							$ 6,900
November 4, 2014, Offering
Subsidiary, Sale of Stock
Shares issued | shares						1,385,000
Net proceeds allocated to equity | $						$ 2,500
November 4, 2014, Offering | Warrants Issued November 4, 2014, Liability
Subsidiary, Sale of Stock
Net proceeds | $						3,800
Gross proceeds | $						$ 4,400
November 4, 2014, Offering | Series A Warrants
Subsidiary, Sale of Stock
Number of shares of stock into which each warrant may be converted (in shares) | shares						0.28
Exercise price (in dollars per share)						$ 3.25
Number of shares into which warrants may be converted (in shares) | shares						388,393
Share price (in dollars per share)						$ 2.80
November 4, 2014, Offering | Series B Warrants
Subsidiary, Sale of Stock
Exercise price (in dollars per share)						$ 0.01
Number of shares into which warrants may be converted (in shares) | shares						168,571
Share price (in dollars per share)						$ 2.79
June 2, 2015, Offering
Subsidiary, Sale of Stock
Maximum units offered for sale | shares			2,500,000
Unit price (in dollars per share)			$ 2.05
Number of shares of stock into which each warrant may be converted (in shares) | shares			1
Share component per unit sold (in shares) | shares			1
Net proceeds allocated to equity | $			$ 3,700
November 23, 2015 Offering
Subsidiary, Sale of Stock
Shares issued | shares		883,862
Share price (in dollars per share)		$ 1.22
Gross proceeds allocated to equity | $		$ 100
November 23, 2015 Offering | Warrants Issued April 4, 2014, Liability
Subsidiary, Sale of Stock
Exercise price (in dollars per share)		$ 1.70
Share price (in dollars per share)		0.94
November 23, 2015 Offering | Warrants Issued November 4, 2014, Liability
Subsidiary, Sale of Stock
Exercise price (in dollars per share)		1.70
Share price (in dollars per share)		0.94
November 23, 2015 Offering | Series A Warrants
Subsidiary, Sale of Stock
Exercise price (in dollars per share)		$ 1.70
Warrant issued for purchase of one common stock purchased through pre-funded warrants | shares		0.3
Number of shares into which warrants may be converted (in shares) | shares		771,000
Period before warrants become exercisable		7 years
Exercise period		5 years
November 23, 2015 Offering | Series B Warrants
Subsidiary, Sale of Stock
Number of shares of stock into which each warrant may be converted (in shares) | shares		1
Exercise price (in dollars per share)		$ 0.01
Number of shares into which warrants may be converted (in shares) | shares		1,686,138
Warrant price (in dollars per share)		$ 1.21
Exercise period		2 years
November 23, 2015 Offering | Warrants Issued November 23, 2015, Liability
Subsidiary, Sale of Stock
Number of shares of stock into which each warrant may be converted (in shares) | shares		1
November 23, 2015 Offering | Series C-1, Series C-2 and Series C-3 Warrants
Subsidiary, Sale of Stock
Exercise price (in dollars per share)		$ 1.70
Number of shares into which warrants may be converted (in shares) | shares		856,393
Period before warrants become exercisable		7 years
Expiration period		7 months
November 23, 2015 Offering | Warrants Issued November 11, 2014, Liability
Subsidiary, Sale of Stock
Exercise price (in dollars per share)									$ 1.22
Shelf Registration
Subsidiary, Sale of Stock
Authorized amount | $								$ 50,000
Maximum percentage of public float for public offering limit								33.00%
Period of public float for public offering limit								12 months
Shelf registration public float threshold | $								$ 75,000
Replacement Shelf
Subsidiary, Sale of Stock
Authorized amount | $				$ 50,000
Maximum percentage of public float for public offering limit				33.00%
Period of public float for public offering limit				12 months
Shelf registration public float threshold | $				$ 75,000