Common Stock Warrants and Common Stock Warrant Liability (Details Narrative) - USD ($) $ / shares in Units, $ in Thousands							1 Months Ended		3 Months Ended		12 Months Ended
	Sep. 13, 2018	Aug. 31, 2018	Aug. 13, 2018	Jul. 24, 2018	Jun. 20, 2018	Nov. 21, 2017	Jun. 30, 2018	Nov. 30, 2017	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Jun. 30, 2015
Warrants exercised									(31,811)
Common Stock Offering Warrants Issued
Exercise price (in dollars per share)									$ 1.15
Share price (in dollars per share)									$ 1.22			$ 0.59
Change in fair value of the derivative warrant liability									$ (5)	$ 13
Fair value adjustment of warrants									1
Stock compensation expense									252	$ 698
Deemed dividend									333
Unexercised warrants									$ 3,181,841
Common Stock Warrants Issued To Participants in Offering of the Company's Common Stock [Member]
Common Stock Offering Warrants Issued					1,133,909
Number of shares purchased					1,133,909	4,657,500			1,133,909
Exercise price (in dollars per share)					$ 1.50	$ 1.50			$ 1.82
Warrant term						5 years
Description of method used						Lattice model
Share price (in dollars per share)						$ 1.00			$ 2.11
Fair value of common stock warrant						$ 661
Expected volatility rate						73.80%	72.60%
Expected term						5 years	5 years
Expected dividend rate						0.00%	0.00%
Risk free interest rate						1.87%	2.80%
Proceeds from warrant exercises					$ 1,700		$ 1,700
Stock compensation expense							1,700
Common Stock Warrant Issued to Underwriter of Common Stock Offering [Member]
Number of shares purchased								945,000
Exercise price (in dollars per share)			$ 0.95	$ 1.47				$ 1.50
Warrant term								5 years
Description of method used								Lattice model
Share price (in dollars per share)			$ 1.02	$ 1.38				$ 1.00
Fair value of common stock warrant								$ 134
Expected volatility rate			74.00%	72.40%				73.80%
Expected term			4 years 3 months	4 years 3 months 29 days				5 years
Expected dividend rate			0.00%	0.00%				0.00%
Risk free interest rate			2.75%	2.83%				1.87%
New Warrants November 8, 2017 [Member]
Number of shares purchased					1,133,909				341,750
Exercise price (in dollars per share)					$ 1.82
Proceeds from warrant exercises							$ 513
University of Arizona Common Stock Warrant [Member]
Number of shares purchased													15,000
Exercise price (in dollars per share)									$ 7.91				$ 7.50
Warrant term									5 years
Description of method used									Monte Carlo option pricing model
Expected volatility rate									77.70%
Expected dividend rate									0.00%
Risk free interest rate									1.93%
Change in fair value of the derivative warrant liability									$ 5
Derivative liability									$ 5				$ 53
Public Offering [Member]
Number of shares purchased						5,860,000
Exercise price (in dollars per share)						$ 1.00
Right Offering [Member]
Common Stock Offering Warrants Issued			5,357,052
Exercise price (in dollars per share)		$ 1.15
Share price (in dollars per share)			$ 0.94
Fair value of common stock warrant			$ 3,600
Expected volatility rate	159.00%
Expected term	5 years
Expected dividend rate	0.00%
Risk free interest rate	2.77%
Number of share issued in transaction			5,357,052
Right Offering [Member] | Warrant [Member] | Maxim Partners LLC [Member]
Common Stock Offering Warrants Issued		267,853
Exercise price (in dollars per share)		$ 1.725
Share price (in dollars per share)			$ 0.94
Fair value of common stock warrant			$ 169
Expected volatility rate			159.00%
Expected term			5 years
Expected dividend rate			0.00%
Risk free interest rate			2.77%