FAIR VALUE MEASUREMENTS (Tables)

3 Months Ended

Mar. 31, 2013

Fair Value Hierarchy for Financial Assets Measured at Fair Value on a Recurring Basis

The following is a summary of cash equivalents and short-term investments by type of instruments as of March 31, 2013 and December 31, 2012 measured at fair value on a recurring basis (in thousands):

	March 31, 2013
	Level 1		Level 2		Level 3		Total
Money market funds	$	6,524	$	—	$	—	$	6,524
Commercial paper		—		11,186		—		11,186
U.S. agency securities		—		57,525		—		57,525
Corporate bonds		—		30,973		—		30,973
Total assets measured at fair value	$	6,524	$	99,684	$	—	$	106,208

	December 31, 2012
	Level 1		Level 2		Level 3		Total
Money market funds	$	13,505	$	-	$	-	$	13,505
Commercial paper		-		9,696		-		9,696
U.S. agency securities		-		56,315		-		56,315
Corporate bonds		-		34,751		-		34,751
Total assets measured at fair value	$	13,505	$	100,762	$	-	$	114,267

- Definition

Tabular disclosure of assets, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, by class that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3).

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