INVESTMENTS (Available-for-sale Securities)

6 Months Ended

Jun. 30, 2011

Available-for-sale Securities

INVESTMENTS

6. INVESTMENTS

     The summary of available-for-sale securities at June 30, 2011, is as follows:

			Gross Unrealized
	Amortized Cost		Gain (Loss)			Fair Value
Commercial paper	$	11,090	$	9		$	11,099
Corporate bonds		43,960		(21	)		43,939
U.S. government backed securities		22,253		13			22,266
Total	$	77,303	$	1		$	77,304

     Investments include $20,266 of long-term U.S. government backed securities that have been classified in investments and other assets on the condensed consolidated balance sheet at June 30, 2011.

     The summary of available-for-sale securities at December 31, 2010, is as follows:

			Gross Unrealized
	Amortized Cost		Gains			Fair Value
Commercial paper	$	29,635	$	7		$	29,642
Corporate bonds		40,694		(18	)		40,676
U.S. government backed securities		15,500		(6	)		15,494
Total	$	85,829	$	(17	)	$	85,812

     Investments include $3,500 of long-term U.S. government backed securities and $2,081 of long-term corporate bonds that have been classified in investments and other assets on the condensed consolidated balance sheet at December 31, 2010.