FAIR VALUE MEASUREMENTS (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair value of financial instruments
Financial assets carried at fair value, total	$ 31	$ 1,819
Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity securities
Fair value of financial instruments
Financial assets carried at fair value, total	31	1,819
Significant Other Observable Inputs (Level 2)
Fair value of financial instruments
Financial assets carried at fair value, total	124,954	110,211
Significant Other Observable Inputs (Level 2) | Money market funds
Fair value of financial instruments
Financial assets carried at fair value, total	1,041	4,469
Significant Other Observable Inputs (Level 2) | Commercial paper
Fair value of financial instruments
Financial assets carried at fair value, total	26,747	31,394
Significant Other Observable Inputs (Level 2) | Corporate notes
Fair value of financial instruments
Financial assets carried at fair value, total	7,921	1,435
Significant Other Observable Inputs (Level 2) | U.S. government and U.S government agency notes
Fair value of financial instruments
Financial assets carried at fair value, total	89,245	72,913
Significant Unobservable Inputs (Level 3)
Fair value of financial instruments
Financial liabilities carried at fair value, total	17,227	29,164
Significant Unobservable Inputs (Level 3) | Deferred acquisition consideration
Fair value of financial instruments
Financial liabilities carried at fair value, total	16,911	28,977
Significant Unobservable Inputs (Level 3) | Warrant liability
Fair value of financial instruments
Financial liabilities carried at fair value, total	316	187
Total
Fair value of financial instruments
Financial assets carried at fair value, total	124,985	112,030
Financial liabilities carried at fair value, total	17,227	29,164
Total | Deferred acquisition consideration
Fair value of financial instruments
Financial liabilities carried at fair value, total	16,911	28,977
Total | Warrant liability
Fair value of financial instruments
Financial liabilities carried at fair value, total	316	187
Total | Money market funds
Fair value of financial instruments
Financial assets carried at fair value, total	1,041	4,469
Total | Commercial paper
Fair value of financial instruments
Financial assets carried at fair value, total	26,747	31,394
Total | Corporate notes
Fair value of financial instruments
Financial assets carried at fair value, total	7,921	1,435
Total | U.S. government and U.S government agency notes
Fair value of financial instruments
Financial assets carried at fair value, total	89,245	72,913
Total | Equity securities
Fair value of financial instruments
Financial assets carried at fair value, total	$ 31	$ 1,819