SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) - USD ($)	Jul. 17, 2012	Jul. 13, 2012	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Short-term investments, Amortized Cost			$ 300,333,000	$ 246,171,000
Short-term investments, Unrealized Gains			4,000	18,000
Short-term investments, Unrealized Losses			(169,000)	(54,000)
Investments			300,168,000	246,135,000
Plextronics, Inc. [Member]
Schedule of Available-for-sale Securities [Line Items]
Joint development, term of agreement (in years)		3 years
Certificates of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis			11,532,000	11,373,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax			3,000	4,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax			(14,000)	(13,000)
Available-for-sale Securities, Fair Value Disclosure			11,521,000	11,364,000
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized Cost			233,848,000	228,799,000
Available-for-sale debt securities, Unrealized Gains			0	14,000
Available-for-sale debt securities, Unrealized Losses			139,000	41,000
Available-for-sale Securities, Debt Securities			233,709,000	228,772,000
U.S. Government bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized Cost			54,953,000	5,999,000
Available-for-sale debt securities, Unrealized Gains			1,000	0
Available-for-sale debt securities, Unrealized Losses			16,000	0
Available-for-sale Securities, Debt Securities			$ 54,938,000	$ 5,999,000
Convertible notes [Member] | Plextronics, Inc. [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized Cost		$ 4,000,000
Convertible promissory note stated interest rate		3.00%
Convertible notes [Member] | Private Company [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized Cost	$ 300,000
Convertible promissory note stated interest rate	5.00%