CASH, CASH EQUIVALENTS AND SHORT TERM INVESTMENTS (Schedule of Cash, Cash Equivalents and Short Term Investments) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Cash And Cash Equivalents [Line Items]
Cost	$ 33,546	$ 15,526
Gross Unrealized Gains	69	24
Gross Unrealized Losses	(119)	(42)
Estimated fair value	33,496	15,508
Cash [Member]
Cash And Cash Equivalents [Line Items]
Cost	9,166	5,890
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated fair value	9,166	5,890
Money market funds [Member]
Cash And Cash Equivalents [Line Items]
Cost	457	301
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated fair value	457	301
Government and agency securities [Member]
Cash And Cash Equivalents [Line Items]
Cost	19,132	6,233
Gross Unrealized Gains	51	14
Gross Unrealized Losses	(96)	(30)
Estimated fair value	19,087	6,217
Corporate debt securities [Member]
Cash And Cash Equivalents [Line Items]
Cost	4,791	3,102
Gross Unrealized Gains	18	10
Gross Unrealized Losses	(23)	(12)
Estimated fair value	$ 4,786	$ 3,100