Common Stock (Details Narrative) - USD ($) $ / shares in Units, $ in Thousands					3 Months Ended
	Dec. 14, 2017	Sep. 27, 2017	Sep. 25, 2017	Apr. 14, 2017	Mar. 31, 2018	Mar. 31, 2017
Proceeds from common stock					$ 651	$ 13,388
Common Stock Purchase Agreement [Member] | Aspire Capital Fund LLC [Member]
Net proceeds from direct offering			$ 22,000
Number of common stock issued	150,000	1,428,571	880,000
Proceeds from common stock	$ 200	$ 2,000
Number of common stock shares issued to commitment fee			880,000
Common Stock Purchase Agreement [Member] | Aspire Capital Fund LLC [Member] | Minimum [Member]
Number of common stock shares issued to commitment fee		880,000
Average price per shares issued		$ 1.38	$ 1.38
May 7, 2018 [Member] | Common Stock Purchase Agreement [Member] | Aspire Capital Fund LLC [Member]
Available for future sales					$ 18,700
Number of common stock issued					1,951,896
Proceeds from common stock					$ 1,100
Remained available future sales					$ 22,000
Number of common stock shares limited to current exchange cap					2,700
ATM Offering [Member]
Net proceeds from direct offering				$ 30,000
Sales commission percentage				2.50%
Available for future sales				$ 28,600
ATM Offering [Member] | May 7, 2018 [Member]
Net proceeds from direct offering					$ 1,400
Number of common stock sold					1,200,565