FAIR VALUE MEASUREMENTS (Tables)

6 Months Ended

Jun. 30, 2013

Fair Value Disclosures [Abstract]

Assets and liabilities carried at fair value measured on a recurring basis

The following table provides the assets carried at fair value measured on a recurring basis as of June 30, 2013 (in thousands):

			Fair Value Measurements, Using
	Total carrying value as of June 30, 2013		Quoted prices in active markets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
Cash equivalents	$	43,998	$	43,998	$	—	$	—
Short-term investments	163,983		163,983		—		—
Long-term investments	5,781		1,481		—		4,300

The following table provides the assets carried at fair value measured on a recurring basis as of December 31, 2012 (in thousands):

			Fair Value Measurements, Using
	Total carrying  value as of December 31, 2012		Quoted prices in active markets  (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
Cash equivalents	$	63,863	$	63,863	$	—	$	—
Short-term investments	158,018		154,018		—		4,000
Long-term investments	1,270		970		—		300

Convertible Notes, unobservable input reconciliation

The following table is a reconciliation of the changes in fair value of the Company’s investments in convertible notes for the three and six months ended June 30, 2013, which had been classified in Level 3 in the fair value hierarchy (in thousands):

	Three Months Ended June 30, 2013		Six Months Ended June 30, 2013
Fair value of notes, beginning of period	$	4,300	$	4,300
Investments	—		—
Fair value of notes, end of period	$	4,300	$	4,300