Equity - (Warrants) (Details) $ / shares in Units, $ in Thousands				1 Months Ended		3 Months Ended
	Feb. 11, 2016 item $ / shares shares	Jan. 19, 2016 item $ / shares shares	Sep. 10, 2014 $ / shares shares	Sep. 30, 2014 $ / shares shares	Sep. 30, 2012 $ / shares shares	Mar. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($)
Weighted Average Exercise Price Per Share
Warrant liability | $						$ 1,390	$ 210
Sentient Loan
Weighted Average Exercise Price Per Share
Stock price trigger (in dollars per share) | $ / shares		$ 0.29
Stock price trigger (as a percent)	90.00%	90.00%
Consecutive trading days, period | item	15	15
Warrant
Number of Underlying Shares
Outstanding at the beginning of year (in shares)						8,777,409
Dilution adjustment						2,266,331
Outstanding at end of year (in shares)						11,043,740
Weighted Average Exercise Price Per Share
Outstanding at beginning of year (in dollars per share) | $ / shares						$ 3.95
Outstanding at end of period (in dollars per share) | $ / shares						3.06
2012 Warrants | Private Placement | Sentient
Number of Underlying Shares
Dilution adjustment	593,564	1,052,784		599,760
Outstanding at end of year (in shares)	5,677,757	5,084,193		4,031,409	3,431,649
Weighted Average Exercise Price Per Share
Outstanding at end of period (in dollars per share) | $ / shares	$ 5.09			$ 7.17	$ 8.42	$ 5.68
Number of shares of common stock per capital unit (in shares)					1
Number of common shares which can be purchased with each warrant					0.5
Term of warrants					5 years
2014 Warrants | Private Placement | Sentient
Number of Underlying Shares
Units Issued During Period New Issues			4,746,000
Dilution adjustment	257,636	362,347
Outstanding at end of year (in shares)	5,365,983	5,108,347
Weighted Average Exercise Price Per Share
Granted during period | $ / shares			$ 1.21
Outstanding at end of period (in dollars per share) | $ / shares	$ 0.91	$ 1.01
Number of shares of common stock per capital unit (in shares)				1
Number of common shares which can be purchased with each warrant				0.5
Term of warrants			5 years
Level 3 | Warrant
Weighted Average Exercise Price Per Share
Warrant liability | $						$ 1,400
Level 3 | 2012 Warrants
Weighted Average Exercise Price Per Share
Warrant liability | $						1,200
Level 3 | 2014 Warrants
Weighted Average Exercise Price Per Share
Warrant liability | $						$ 200