Short-Term Investments (Tables)

12 Months Ended

Dec. 31, 2012

Short-term Investments [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.

	December 31, 2012
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
Cash	$	284,661	$	—	$	—		$	284,661
Level 1 securities:
Money market funds	10,500		—		—			10,500
Level 2 securities:
Corporate debt securities	150,322		1,605		(32		)	151,895
Government and agency securities	166,643		285		—			166,928
Asset and mortgage-backed securities	138,340		750		(125		)	138,965
Total (1)	$	750,466	$	2,640	$	(157	)	$	752,949

	December 31, 2011
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
Cash	$	388,941	$	—	$	—		$	388,941
Level 1 securities:
Money market funds	123,608		—		—			123,608
Level 2 securities:
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
Total (2)	$	801,218	$	1,359	$	(270	)	$	802,307

(1) Includes $290.3 million that is included in cash and cash equivalents, $457.8 million included in short-term investments and $4.8 million of restricted cash that is included in other non-current assets related to workers compensation deposits.

(2) Includes $508.1 million included in cash and cash equivalents, $289.8 million included in short-term investments and $4.5 million of restricted cash that is included in other current assets and other non-current assets.

F

Estimated Fair Value Of Short-Term Investments By Contractual Maturity

he estimated fair value of short-term investments by contractual maturity as of December 31, 2012 is as follows:

	(in thousands)
Due within one year	$	94,739
Due after one year and through 5 years	312,096
Due after 5 years and through 10 years	6,679
Due after 10 years	44,273
Total short-term investments	$	457,787