MARKETABLE SECURITITES Marketable Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 90,303	$ 83,866
Gross Unrealized Gains	137	8
Gross Unrealized Losses	(21)	(105)
Estimated Fair Market Value	90,419	83,769
Investments due in less than 3 months:
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	14,443	38,586
Gross Unrealized Gains	4	7
Gross Unrealized Losses	(2)	(10)
Estimated Fair Market Value	14,445	38,583
Investments due in 4-12 months:
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	28,540	33,654
Gross Unrealized Gains	23	1
Gross Unrealized Losses	(6)	(36)
Estimated Fair Market Value	28,557	33,619
Investments due between 12 months and 5-years:
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	47,320	11,626
Gross Unrealized Gains	110	0
Gross Unrealized Losses	(13)	(59)
Estimated Fair Market Value	47,417	11,567
Corporate securities | Investments due in less than 3 months:
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	14,443	38,586
Gross Unrealized Gains	4	7
Gross Unrealized Losses	(2)	(10)
Estimated Fair Market Value	14,445	38,583
Corporate securities | Investments due in 4-12 months:
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	28,540	33,654
Gross Unrealized Gains	23	1
Gross Unrealized Losses	(6)	(36)
Estimated Fair Market Value	28,557	33,619
Corporate securities | Investments due between 12 months and 5-years:
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	47,320	11,626
Gross Unrealized Gains	110	0
Gross Unrealized Losses	(13)	(59)
Estimated Fair Market Value	$ 47,417	$ 11,567