Short-Term Investments And Fair Value Measurement (Tables)

3 Months Ended

Mar. 31, 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
	March 31, 2012
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
Cash	$	394,726	$	—	$	—		$	394,726
Level 1 securities (1):
Money market funds	6,134		—		—			6,134
Level 2 securities (3):
Corporate debt securities	104,998		769		(65		)	105,702
Government and agency securities	253,897		417		(147		)	254,167
Asset and mortgage-backed securities	48,452		228		(15		)	48,665
	$	808,207	$	1,414	$	(227	)	$	809,394
Less: Long-term restricted cash (1)								(4,868		)
Total cash, cash equivalents and short-term investments								$	804,526

	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: Long-term restricted cash (2)								(4,496		)
Total cash, cash equivalents and short-term investments								$	797,811

(1) Includes $1.2 million classified in cash and cash equivalents and $4.9 million classified in other non-current assets.

(2) Includes $119.1 million classified in cash and cash equivalents and $4.5 million 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 March 31, 2012 is as follows:

	(in thousands)
Due within one year	$	48,650
Due after one year and through 5 years	329,494
Due after 5 years and through 10 years	10,191
Due after 10 years	20,199
Total short-term investments	$	408,534