Cash, Cash Equivalents, Short-Term Investments And Fair Value Measurment (Tables)

6 Months Ended

Jun. 30, 2012

Short-Term Investments And Fair Value Measurement [Abstract]

Available-For-Sale Securities Reported At Fair Value

The following table summarizes, by major security type, the Company’s assets that are measured at fair value on a recurring basis and are categorized using the fair value hierarchy:

	As of
	June 30, 2012
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
Cash	$	402,192	$	—	$	—		$	402,192
Level 1 securities (1):
Money market funds	4,928		—		—			4,928
Level 2 securities (3):
Corporate debt securities	108,956		807		(20		)	109,743
Government and agency securities	210,477		281		(38		)	210,720
Asset and mortgage-backed securities	90,226		420		(17		)	90,629
	$	816,779	$	1,508	$	(75	)	$	818,212
Less: Restricted cash (1)								(4,869		)
Total cash, cash equivalents and short-term investments								$	813,343

	As of
	December 31, 2011
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
Cash	$	388,941	$	—	$	—		$	388,941
Level 1 securities (2):
Money market funds	123,608		—		—			123,608
Level 2 securities (3):
Corporate debt securities	112,264		603		(214		)	112,653
Government and agency securities	175,464		694		(56		)	176,102
Asset and mortgage-backed securities	941		62		—			1,003
	$	801,218	$	1,359	$	(270	)	$	802,307
Less: Restricted cash (2)								(4,496		)
Total cash, cash equivalents and short-term investments								$	797,811

(1) Includes $4.9 million of restricted cash classified in other non-current assets.

(2) Includes $119.1 million classified in cash and cash equivalents and $4.5 million of restricted cash classified in other current assets and non-current assets.

(3) Included in short-term investments.

Estimated Fair Value Of Short-Term Investments By Contractual Maturity

The estimated fair value of short-term investments by contractual maturity as of June 30, 2012 is as follows:

	(in thousands)
Due within one year	$	15,676
Due after one year and through 5 years	355,328
Due after 5 years and through 10 years	9,223
Due after 10 years	30,865
Total short-term investments	$	411,092