Fair Value Measurements

3 Months Ended

Mar. 31, 2013

Fair Value Measurements [Abstract]

Fair Value Measurements

3. Fair Value Measurements

We measure our cash equivalents and marketable securities at fair value. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three-tier fair value hierarchy is established as a basis for considering such assumptions and for inputs used in the valuation methodologies in measuring fair value:

Level 1: Quoted prices in active markets for identical assets or liabilities.

Level 2: Directly or indirectly observable market-based inputs or unobservable inputs used in models or other valuation methodologies.

Level 3: Unobservable inputs that are not corroborated by market data. The inputs require significant management judgment or estimation.

We classify our cash equivalents and marketable securities within Level 1 or Level 2 because our cash equivalents and marketable securities are valued using quoted market prices or alternative pricing sources and models utilizing market observable inputs.

Assets and liabilities measured at fair value on a recurring basis as of March 31, 2013 and December 31, 2012 are summarized below (in thousands):

	March 31, 2013
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Direct or Indirect Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets
Cash equivalents:
Money market funds	$	5,938	$	—	$	—	$	5,938
Total cash equivalents		5,938		—		—		5,938
Short-term investments:
Municipal Securities		—		—		—		—
Corporate commercial paper		—		1,475		—		1,475
Foreign government bonds		—		1,000		—		1,000
Corporate debt securities		—		6,770		—		6,770
Total short-term investments		—		9,245		—		9,245
Restricted cash—money market fund		875		—		—		875
Total assets measured at fair value	$	6,813	$	9,245	$	—	$	16,058

	December 31, 2012
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Direct or Indirect Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets
Cash equivalents:
Money market funds	$	7,313	$	—	$	—	$	7,313
Total cash equivalents		7,313		—		—		7,313
Short-term investments:
Municipal securities		—		356		—		356
Corporate commercial paper		—		4,374		—		4,374
Foreign government bonds		—		999		—		999
Corporate debt securities		—		4,097		—		4,097
Total short-term investments		—		9,826	$	—		9,826
Restricted cash—money market fund		875		—		—		875
Total assets measured at fair value	$	8,188	$	9,826	$	—	$	18,014