STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]		Additional paid-in capital [Member]	Receipts on account of shares [Member]	Accumulated Deficit [Member]
Balance at Dec. 31, 2017	$ 5,880	$ 11		$ 85,944	$ 0	$ (80,075)
Balance (in shares) at Dec. 31, 2017		18,976,169
Stock-based compensation related to warrants and stock granted to service providers	102		[1]	102	0	0
Stock-based compensation related to warrants and stock granted to service providers (in shares)		42,293
Stock-based compensation related to stock and options granted to directors and employees	917		[1]	917	0	0
Stock-based compensation related to stock and options granted to directors and employees (in shares)		147,820
Exercise of options	25		[1]	25	0	0
Exercise of options (in shares)		33,332
Exercise and reissuance of warrants	12,040		[1]	7,632	4,408	0
Exercise and reissuance of warrants (in shares)		1,558,202
Net loss	(13,948)	$ 0		0	0	(13,948)
Balance at Dec. 31, 2018	5,016	$ 11		94,620	4,408	(94,023)
Balance (in shares) at Dec. 31, 2018		20,757,816
Stock-based compensation related to warrants and stock granted to service providers	25		[1]	25	0	0
Stock-based compensation related to warrants and stock granted to service providers (in shares)		5,908
Stock-based compensation related to stock and options granted to directors and employees	312		[1]	312	0	0
Stock-based compensation related to stock and options granted to directors and employees (in shares)		39,386
Exercise and reissuance of warrants	0		[1]	3,368	(3,368)	0
Exercise and reissuance of warrants (in shares)		687,500
Net loss	(5,027)	$ 0		0	0	(5,027)
Balance at Mar. 31, 2019	$ 326	$ 11		$ 98,325	$ 1,040	$ (99,050)
Balance (in shares) at Mar. 31, 2019		21,490,610

[1] Represents an amount less than $1.