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Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2011

Marketable Securities

Cash equivalents and marketable securities classified as available-for-sale

		June 30, 2011
(Dollars in thousands)		Fair Value			Amortized Cost			Gross Unrealized Gains			Gross Unrealized Losses			Weighted Rate of Return
Money market funds		$	168,847		$	168,847		$	—		$	—		0.01	%
U.S. government bonds and notes		65,592			65,569			23			—			0.22	%
Corporate notes, bonds and commercial paper		113,958			114,020			2			(64		)	0.40	%
Total cash equivalents and marketable securities		348,397			348,436			25			(64		)
Cash		10,957			10,957			—			—
Total cash, cash equivalents and marketable securities		$	359,354		$	359,393		$	25		$	(64	)

		December 31, 2010
(Dollars in thousands)		Fair Value			Amortized Cost			Gross Unrealized Gains			Gross Unrealized Losses			Weighted Rate of Return
Money market funds		$	132,364		$	132,364		$	—		$	—		0.04	%
U.S. government bonds and notes		266,817			266,840			29			(52		)	0.26	%
Corporate notes, bonds and commercial paper		95,724			95,773			8			(57		)	0.39	%
Total cash equivalents and marketable securities		494,905			494,977			37			(109		)
Cash		17,104			17,104			—			—
Total cash, cash equivalents and marketable securities		$	512,009		$	512,081		$	37		$	(109	)

Available-for-sale securities reported at fair value

		June 30,  2011			December 31,  2010
		(in thousands)
Cash equivalents		$	168,847		$	198,158
Short term marketable securities		179,550			296,747
Total cash equivalents and marketable securities		348,397			494,905
Cash		10,957			17,104
Total cash, cash equivalents and marketable securities		$	359,354		$	512,009

Estimated fair value of cash equivalents and marketable securities classified by date of contractual maturity and the associated unrealized gain, net

		As of						Unrealized Loss, net
		June 30, 2011			December 31, 2010			June 30, 2011			December 31, 2010
		(in thousands)
Contractual maturity:
Due within one year		$	348,397		$	494,905		$	(39	)	$	(72	)

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