SIGNIFICANT ACCOUNTING POLICIES 3 (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jan. 01, 2017 USD ($)	Dec. 31, 2016 USD ($)
Redeemable Convertible Preferred Stock [Roll Forward]
Beginning Balance		$ 34,859	$ 32,143
Issuance of redeemable convertible preferred stock, less issuance costs and warrant		7,311
Deemed dividend on redeemable convertible preferred stock		(3,493)	(2,716)
Less issuance costs, net of accretion		(396)	0
Ending Balance		45,663	34,859
Cash, cash equivalents, and restricted cash		25,650	11,932		$ 13,689
Net cash used in operating activities		(14,651)	(11,360)
Net cash (used in) provided by investing activities		(11,000)	43,512
Series A Preferred Stock [Member]
Redeemable Convertible Preferred Stock [Roll Forward]
Beginning Balance		0
Issuance of redeemable convertible preferred stock, less issuance costs and warrant		22,000
Less issuance costs, net of accretion		(253)
Ending Balance		$ 21,747	0
Series B Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock redemption price		150.00%
Series B-1 and B-2 Cumulative Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock conversion ratio		1
Preferred stock redemption period		5 years
Preferred stock redemption price		150.00%
Series B-1 and B-2 Cumulative Convertible Preferred Stock [Member] | Subsequent Event [Member]
Class of Stock [Line Items]
Preferred stock redemption price	160.00%
Series B-3 Cumulative Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock conversion ratio		1
Preferred stock redemption period		5 years
Preferred stock redemption price		145.00%
Accounting Standards Update 2016-18 [Member]
Redeemable Convertible Preferred Stock [Roll Forward]
Cash, cash equivalents, and restricted cash			2,200	$ 0
Net cash used in operating activities			(2,000)
Net cash (used in) provided by investing activities			$ (100)