SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Available-for-sale Investments) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 152,941	$ 112,068
Gross Unrealized Gains	269	236
Gross Unrealized Losses	(66)	(26)
Estimated Fair Market Value	153,144	112,278
Investments due in less than 3 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	6,000	3,098
Gross Unrealized Gains	3	1
Gross Unrealized Losses	0	0
Estimated Fair Market Value	6,003	3,099
Investments due in 4-12 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	37,175	6,007
Gross Unrealized Gains	62	33
Gross Unrealized Losses	0	0
Estimated Fair Market Value	37,237	6,040
Investments due in more than 12 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	109,766	102,963
Gross Unrealized Gains	204	202
Gross Unrealized Losses	(66)	(26)
Estimated Fair Market Value	109,904	103,139
Commercial paper [Member] | Investments due in less than 3 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost		3,098
Gross Unrealized Gains		1
Gross Unrealized Losses		0
Estimated Fair Market Value		3,099
Corporate securities [Member] | Investments due in less than 3 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	6,000
Gross Unrealized Gains	3
Gross Unrealized Losses	0
Estimated Fair Market Value	6,003
Corporate securities [Member] | Investments due in 4-12 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	37,175	6,007
Gross Unrealized Gains	62	33
Gross Unrealized Losses	0	0
Estimated Fair Market Value	37,237	6,040
Corporate securities [Member] | Investments due in more than 12 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	109,766	102,963
Gross Unrealized Gains	204	202
Gross Unrealized Losses	(66)	(26)
Estimated Fair Market Value	$ 109,904	$ 103,139