Convertible Preferred Stock and Stockholders' Equity - Summary of Option and Stock Appreciation Rights Activity (Details)	6 Months Ended
	Jun. 30, 2018 $ / shares shares
Number of Options/SARs, Outstanding, Beinning Balance | shares	413,301
Number of Options/SARs, Granted | shares	858,500
Number of Options/SARs, Exercised | shares
Number of Options/SARs, Forfeited | shares	(104,026)
Number of Options/SARs, Outstanding, Ending Balance | shares	1,167,775
Weighted Average Exercise Price per Share, Outstanding, Beginning Balance	$ 9.04
Weighted Average Exercise Price per Share, Granted	0.74
Weighted Average Exercise Price per Share, Exercised
Weighted Average Exercise Price per Share, Forfeited	10.02
Weighted Average Exercise Price per Share, Outstanding, Ending Balance	2.85
Range One [Member]
Range of Exercise Price, Lower Limit	0.62
Range of Exercise Price, Upper Limit	54.90
Range Two [Member]
Range of Exercise Price, Lower Limit	0.74
Range of Exercise Price, Upper Limit	0.83
Range Three [Member]
Range of Exercise Price, Lower Limit	0.74
Range of Exercise Price, Upper Limit	54.90
Range Four [Member]
Range of Exercise Price, Lower Limit	0.62
Range of Exercise Price, Upper Limit	$ 43.90