Fair Value Measurements

12 Months Ended

Dec. 31, 2011

Fair Value Measurements [Abstract]

Fair Value Measurements

4. Fair Value Measurements

The Company's financial assets are valued using market prices on both active markets ("Level 1") and less active markets ("Level 2"). Level 1 instrument valuations are obtained from real-time quotes for transactions in active exchange markets involving identical assets. Level 2 instrument valuations are obtained from readily available pricing sources for comparable instruments. As of December 31, 2011 and 2010, the Company did not have any financial assets without observable market values that would require a high level of judgment to determine fair value ("Level 3").

The following tables present the financial assets measured at fair value on a recurring basis as of December 31, 2011 and 2010 (in thousands):

	December 31, 2011
	Total Balance		Level 1		Level 2
Cash equivalents (1)
Money market funds	$	21,504	$	21,504	$	—
Commercial paper		24,405		—		24,405
Municipal bonds		8,385		—		8,385
Corporate bonds		2,045		—		2,045
	$	56,339	$	21,504	$	34,835
Short-term investments
Commercial paper	$	4,850	$	—	$	4,850
Municipal bonds		65,675		—		65,675
Corporate bonds		6,828		—		6,828
U.S. government and agency securities		49,623		—		49,623
	$	126,976	$	—	$	126,976

	December 31, 2010
	Total Balance		Level 1		Level 2
Money market funds (1)	$	36,560	$	36,560	$	—

⁽¹⁾  These assets are included within cash and cash equivalents in the consolidated balance sheets.