FAIR VALUE MEASUREMENTS (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2011 Stock warrant [Member] Decimal	Jun. 30, 2011 Stock warrant liability [Member]	Jun. 30, 2011 Stock warrant liability [Member]	Jun. 30, 2012 Stock warrant liability [Member]	Jun. 30, 2012 Quoted prices in active markets (Level 1) [Member]	Dec. 31, 2011 Quoted prices in active markets (Level 1) [Member]	Jun. 30, 2012 Significant other observable inputs (Level 2) [Member]	Dec. 31, 2011 Significant other observable inputs (Level 2) [Member]	Jun. 30, 2012 Significant unobservable inputs (Level 3) [Member]	Dec. 31, 2011 Significant unobservable inputs (Level 3) [Member]	Jun. 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					$ 141,478	$ 96,538	$ 0	$ 0	$ 0	$ 0	$ 141,478	$ 96,538
Short-term investments					190,417	234,294	0	0	0	0	190,417	234,294
Investments					1,172		0		0		1,172
Reconciliation of changes in fair value classified as Level 3 [Roll Forward]
Fair value of stock warrant liability, beginning of period				13,110
Loss for period		(4,496)	4,430
Warrants exercised		(4,025)	(10,501)
Fair value of stock warrant liability, end of period		$ 10,660	$ 10,660	$ 13,110
Derivative [Line Items]
Contractual life (years)	0.1
Expected volatility (in hundredths)	87.40%
Risk-free interest rate (in hundredths)	2.00%
Annual dividend yield (in hundredths)	0.00%