OTHER CURRENT ASSETS AND LONG-TERM ASSETS (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid expenses	$ 1,261	$ 3,085
Deposits and other receivables	1,841	1,600
Interest receivables	768	237
Other current assets	3,870	4,922
Other Assets, Noncurrent [Abstract]
Deposits paid for research and development	$ 1,300	$ 1,000