FAIR VALUE MEASUREMENTS (Details) (USD $) In Thousands, unless otherwise specified				3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Sep. 30, 2011 Stock warrant liability [Member]	Sep. 30, 2011 Stock warrant liability [Member]	Sep. 30, 2012 Convertible Notes Receivable [Member]	Sep. 30, 2012 Convertible Notes Receivable [Member]	Sep. 30, 2012 Quoted prices in active markets (Level 1) [Member]	Dec. 31, 2011 Quoted prices in active markets (Level 1) [Member]	Sep. 30, 2012 Significant other observable inputs (Level 2) [Member]	Dec. 31, 2011 Significant other observable inputs (Level 2) [Member]	Sep. 30, 2012 Significant unobservable inputs (Level 3) [Member]	Dec. 31, 2011 Significant unobservable inputs (Level 3) [Member]	Sep. 30, 2012 Total carrying value [Member]	Dec. 31, 2011 Total carrying value [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents								$ 64,228	$ 96,538					$ 64,228	$ 96,538
Short-term investments								160,585	234,294			4,000		164,585	234,294
Investments								869				300		1,169
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of notes, beginning of period	4,300
Investments						4,300	4,300
Fair value of notes, end of period	4,300
Reconciliation of changes in fair value classified as Level 3 [Roll Forward]
Fair value of stock warrant liability, beginning of period		10,660	4,589
Loss for period				(240)	4,190
Warrants exercised				(4,349)	(14,850)
Fair value of stock warrant liability, end of period		$ 10,660	$ 4,589