SIGNIFICANT ACCOUNTING POLICIES (Marketable Securities) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Marketable Securities [Line Items]
Total cash equivalents	$ 2,395	$ 8,126
Short-term marketable securities	42,421	52,856
Total financial assets	44,816	60,982
Total marketable securities and cash equivalents	44,816	60,982
U.S. Treasury securities
Marketable Securities [Line Items]
Short-term marketable securities	12,406	10,133
Corporate notes and bonds
Marketable Securities [Line Items]
Short-term marketable securities	26,678	38,036
Commercial paper
Marketable Securities [Line Items]
Short-term marketable securities	3,337	4,687
Commercial paper
Marketable Securities [Line Items]
Total cash equivalents	$ 2,395	$ 8,126