SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Available-for-sale Investments) (Details) - USD ($) $ in Thousands		Jun. 30, 2015		Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized cost		$ 129,882		$ 114,492
Gross Unrealized Gains		64		128
Gross Unrealized Losses		(18)		(45)
Estimated Fair Market Value		129,928		114,575
Investments due in less than 3 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost		37,792
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Estimated Fair Market Value		37,792
Investments due in 4-12 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost		76,010		30,233
Gross Unrealized Gains		53		36
Gross Unrealized Losses		(11)		0
Estimated Fair Market Value		76,052		30,269
Investments due in more than 12 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost		16,080		84,259
Gross Unrealized Gains		11		92
Gross Unrealized Losses		(7)		(45)
Estimated Fair Market Value		16,084		84,306
Commercial paper [Member] | Investments due in less than 3 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	[1]	34,984
Gross Unrealized Gains	[1]	0
Gross Unrealized Losses	[1]	0
Estimated Fair Market Value	[1]	34,984
Commercial paper [Member] | Investments due in 4-12 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	[2]	7,488
Gross Unrealized Gains	[2]	0
Gross Unrealized Losses	[2]	0
Estimated Fair Market Value	[2]	7,488
Corporate securities [Member] | Investments due in less than 3 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	[2]	2,808
Gross Unrealized Gains	[2]	0
Gross Unrealized Losses	[2]	0
Estimated Fair Market Value	[2]	2,808
Corporate securities [Member] | Investments due in 4-12 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost		68,522	[2]	30,233
Gross Unrealized Gains		53	[2]	36
Gross Unrealized Losses		(11)	[2]	0
Estimated Fair Market Value		68,564	[2]	30,269
Corporate securities [Member] | Investments due in more than 12 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost		16,080	[2]	84,259
Gross Unrealized Gains		11	[2]	92
Gross Unrealized Losses		(7)	[2]	(45)
Estimated Fair Market Value		$ 16,084	[2]	$ 84,306

[1] (1)Included within cash and cash equivalents on the condensed consolidated balance sheet.

[2] (2)Included within short-term marketable securities on the condensed consolidated balance sheet.