SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Available-for-sale Investments) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 133,405	$ 112,068
Gross Unrealized Gains	450	236
Gross Unrealized Losses	(1)	(26)
Estimated Fair Market Value	133,854	112,278
Investments due in less than 3 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	500	3,098
Gross Unrealized Gains	0	1
Gross Unrealized Losses	0	0
Estimated Fair Market Value	500	3,099
Investments due in 4-12 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	40,509	6,007
Gross Unrealized Gains	99	33
Gross Unrealized Losses	0	0
Estimated Fair Market Value	40,608	6,040
Investments due in more than 12 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	92,396	102,963
Gross Unrealized Gains	351	202
Gross Unrealized Losses	(1)	(26)
Estimated Fair Market Value	92,746	103,139
Commercial paper [Member] | Investments due in less than 3 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	500	3,098
Gross Unrealized Gains	0	1
Gross Unrealized Losses	0	0
Estimated Fair Market Value	500	3,099
Corporate securities [Member] | Investments due in 4-12 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	40,509	6,007
Gross Unrealized Gains	99	33
Gross Unrealized Losses	0	0
Estimated Fair Market Value	40,608	6,040
Corporate securities [Member] | Investments due in more than 12 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	92,396	102,963
Gross Unrealized Gains	351	202
Gross Unrealized Losses	(1)	(26)
Estimated Fair Market Value	$ 92,746	$ 103,139