Equity - Warrants (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended			6 Months Ended
	May 31, 2016	Sep. 30, 2014	Sep. 30, 2012	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2016	Oct. 31, 2015
Weighted Average Exercise Price Per Share
Warrant liability					$ 1.5	$ 1.9
Warrant
Number of Underlying Shares
Outstanding, beginning balance (in shares)				11,478,172
Dilution adjustment (in shares)				39,524
Outstanding, end balance (in shares)				11,517,696
Weighted Average Exercise Price Per Share
Outstanding, beginning balance (in dollars per share)				$ 0.81
Dilution adjustment (in dollars per share)				0.87
Outstanding, end balance (in dollars per share)				$ 0.81
2012 Warrants
Weighted Average Exercise Price Per Share
Term of warrants			5 years
2014 Warrants
Number of Underlying Shares
Dilution adjustment (in shares)				771,696
Outstanding, end balance (in shares)				5,517,696
Weighted Average Exercise Price Per Share
Outstanding, end balance (in dollars per share)				$ 0.85
Sentient
Weighted Average Exercise Price Per Share
Principal amount of loan							$ 5.0
Sentient | 2014 Warrants
Weighted Average Exercise Price Per Share
Outstanding, end balance (in dollars per share)		$ 1.21
Number of shares of common stock per capital unit (in shares)		1
Term of warrants		5 years
Number of common shares which can be purchased with each warrant		0.5
Registered Offering
Weighted Average Exercise Price Per Share
Sale price (in dollars per shares)	$ 0.50
Common stock issued (in shares)	8,000,000
Gross proceeds from common stock sale	$ 4.0
Registered Offering | 2016 Warrants
Number of Underlying Shares
Outstanding, end balance (in shares)	6,000,000
Weighted Average Exercise Price Per Share
Granted (in dollars per share)	$ 0.75
Number of shares of common stock per capital unit (in shares)	0.75
Term of warrants	5 years