Fair Value Measurements

3 Months Ended

Mar. 31, 2014

Fair Value Disclosures [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 March 31, 2014 and December 31, 2013 are summarized below (in thousands):

	March 31, 2014
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Direct or Indirect Observable Inputs (Level 2)		Total
Assets
Cash equivalents:
Money market funds	$	12,435	$	—	$	12,435
Corporate commercial paper		—		1,250		1,250
Corporate debt		—		652		652
Total cash equivalents		12,435		1,902		14,337
Short-term investments:
Corporate commercial paper		—		1,250		1,250
Corporate debt securities		—		4,881		4,881
Total short-term investments		—		6,131		6,131
Restricted cash—money market fund		250		—		250
Total assets measured at fair value	$	12,685	$	8,033	$	20,718

	December 31, 2013
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Direct or Indirect Observable Inputs (Level 2)		Total
Assets
Cash equivalents:
Money market funds	$	8,989	$	—	$	8,989
Corporate debt		—		2,000		2,000
Total cash equivalents		8,989		2,000		10,989
Short-term investments:
Corporate commercial paper		—		1,500		1,500
Foreign government bonds		—		1,001		1,001
Corporate debt securities		—		4,794		4,794
Total short-term investments		—		7,295		7,295
Restricted cash—money market fund		250		—		250
Total assets measured at fair value	$	9,239	$	9,295	$	18,534