Fair Value Measurements

6 Months Ended

Jun. 30, 2013

Fair Value Measurements [Abstract]

Fair Value Measurements

3. Fair Value Measurements

We measure our cash equivalents and short-term investments 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 short-term investments within Level 1 or Level 2 because our cash equivalents and short-term investments 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 June 30, 2013 and December 31, 2012 are summarized below (in thousands):

	June 30, 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	$	8,777	$	—	$	—	$	8,777
Total cash equivalents		8,777		—		—		8,777
Short-term investments:
Corporate commercial paper		—		1,250		—		1,250
Foreign government bonds		—		1,001		—		1,001
Corporate debt securities		—		7,080		—		7,080
Total short-term investments		—		9,331		—		9,331
Restricted cash—money market fund		875		—		—		875
Total assets measured at fair value	$	9,652	$	9,331	$	—	$	18,983

	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