FAIR VALUE MEASUREMENTS (Tables)

12 Months Ended

Dec. 31, 2014

Fair Value Disclosures [Abstract]

Assets and Liabilities Measured and Carried at Fair Value

The tables below present information about the Company’s financial assets and liabilities that are measured and carried at fair value and indicate the level within the fair value hierarchy of the valuation techniques it utilizes to determine such fair value:

	Fair Value Measurement as of December 31, 2014
	Total		Level 1		Level 2		Level 3
	(in thousands)
Money market funds	$	47,740	$	47,740	$	—	$	—
Commercial paper		2,997		—		2,997		—
Government and government agency bonds		75,250		—		75,250		—
Corporate bonds		58,546		—		58,546		—
Certificates of deposit		647		647		—		—
Total assets	$	185,180	$	48,387	$	136,793	$	—

	Fair Value Measurement as of December 31, 2013
	Total		Level 1		Level 2		Level 3
	(in thousands)
Money market funds	$	185,000	$	185,000	$	—	$	—
Certificates of deposit		7,897		7,897		—		—
Total assets	$	192,897	$	192,897	$	—	$	—

	Fair Value Measurement as of December 31, 2014
	Total		Level 1		Level 2		Level 3
	(in thousands)
Warrants	$	—	$	—	$	—	$	—
Total liabilities	$	—	$	—	$	—	$	—

	Fair Value Measurement as of December 31, 2013
	Total		Level 1		Level 2		Level 3
	(in thousands)
Warrants	$	9,006	$	—	$	—	$	9,006
Total liabilities	$	9,006	$	—	$	—	$	9,006