CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Ordinary shares [Member]	Additional Paid-in Capital [Member]	Accumulated deficit [Member]	Accumulated other comprehensive Income (loss) [Member]	Total
Balance at Dec. 31, 2017	$ 1,576	$ 208,364	$ (141,281)	$ (58)	$ 68,601
Balance (shares) at Dec. 31, 2017	37,498,128
Impact of initial adoption of new accounting standards, as previously reported			35	(35)
CHANGES DURING THE PERIOD:
Comprehensive loss			(44,605)	(34)	(44,639)
Issuance of shares less offering expenses in the amount of $39K	$ 134	15,997			16,131
Issuance of shares less offering expenses in the amount of $39K (shares)	2,940,000
Exercise of warrants into Ordinary Shares	$ 8	832			840
Exercise of warrants into Ordinary Shares (shares)	178,468
Exercise of options and restricted share units	$ 3	7			10
Exercise of options and restricted share units (shares)	76,883
Share-based compensation (Note 5)		2,954			2,954
Balance at Jun. 30, 2018	$ 1,721	228,154	(185,851)	(127)	43,897
Balance (shares) at Jun. 30, 2018	40,693,479
Balance at Mar. 31, 2018	$ 1,578	210,116	(167,223)	(127)	44,344
Balance (shares) at Mar. 31, 2018	37,551,511
CHANGES DURING THE PERIOD:
Comprehensive loss			(18,628)		(18,628)
Issuance of shares less offering expenses in the amount of $39K	$ 134	15,997			16,131
Issuance of shares less offering expenses in the amount of $39K (shares)	2,940,000
Exercise of warrants into Ordinary Shares	$ 8	832			840
Exercise of warrants into Ordinary Shares (shares)	178,468
Exercise of options and restricted share units	$ 1	9			10
Exercise of options and restricted share units (shares)	23,500
Share-based compensation (Note 5)		1,200			1,200
Balance at Jun. 30, 2018	$ 1,721	228,154	(185,851)	(127)	43,897
Balance (shares) at Jun. 30, 2018	40,693,479
Balance at Dec. 31, 2018	$ 2,331	305,303	(215,409)	(43)	$ 92,182
Balance (shares) at Dec. 31, 2018	54,351,140				54,351,140
CHANGES DURING THE PERIOD:
Comprehensive loss			(34,197)	42	$ (34,155)
Exercise of options and restricted share units	$ 5	13			18
Exercise of options and restricted share units (shares)	104,829
Share-based compensation (Note 5)		2,337			2,337
Balance at Jun. 30, 2019	$ 2,336	307,653	(249,606)	(1)	$ 60,382
Balance (shares) at Jun. 30, 2019	54,455,969				54,455,969
Balance at Mar. 31, 2019	$ 2,334	306,266	(230,613)	8	$ 77,995
Balance (shares) at Mar. 31, 2019	54,419,323
CHANGES DURING THE PERIOD:
Comprehensive loss			(18,993)	(9)	(19,002)
Exercise of options and restricted share units	$ 2				2
Exercise of options and restricted share units (shares)	36,646
Share-based compensation (Note 5)		1,387			1,387
Balance at Jun. 30, 2019	$ 2,336	$ 307,653	$ (249,606)	$ (1)	$ 60,382
Balance (shares) at Jun. 30, 2019	54,455,969				54,455,969