Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2011

Fair Value Measurements

Schedule of assets measured at fair value on a recurring basis

	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents (1)	$	55,239	$	48,073	$	7,166	$	—
Corporate debt securities (2)	207,997		—		207,997		—
Debt securities issued by U.S. government agencies (2)	77,832		—		77,832		—
Debt securities issued by the U.S. Treasury (2)	4,512		4,512		—		—
Debt securities issued by states of the United States and political subdivisions of the states (2)	19,159		—		19,159		—
Equity securities (3)	1,169		1,169		—		—
Total	$	365,908	$	53,754	$	312,154	$	—

(1)Included in cash and cash equivalents on our condensed consolidated balance sheet.

(2)Included in short-term investments on our condensed consolidated balance sheet.

(3)Included in other current assets on our condensed consolidated balance sheet.