Short-term Investments (Tables)

9 Months Ended

Sep. 30, 2014

Short-Term Investments And Fair Value Measurement [Abstract]

Available-For-Sale Securities Reported At Fair Value

The following tables summarize, 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 September 30, 2014
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
Cash	$	1,065,988	$	—	$	—		$	1,065,988
Level 1 securities:
Money market funds	122,936		—		—			122,936
Level 2 securities:
Corporate debt securities	292,410		718		(99		)	293,029
Government securities	166,991		169		(53		)	167,107
Asset-backed securities	370		—		—			370
Certificate of deposits and commercial paper	6,605		—		—			6,605
Agency securities	16,483		8		—			16,491
Total (1)	$	1,671,783	$	895	$	(152	)	$	1,672,526

	As of December 31, 2013
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
Cash	$	483,959	$	—	$	—		$	483,959
Level 1 securities:
Money market funds	126,208		—		—			126,208
Level 2 securities:
Corporate debt securities	316,465		1,245		(654		)	317,056
Government securities	143,812		287		(18		)	144,081
Asset and mortgage-backed securities	93,118		229		(418		)	92,929
Certificate of deposits	23,425		—		—			23,425
Agency securities	17,951		—		(2		)	17,949
Total (2)	$	1,204,938	$	1,761	$	(1,092	)	$	1,205,607

(1) Includes $1,183.2 million that is included in cash and cash equivalents, $483.6 million included in short-term investments and $5.7 million of restricted cash that is included in other non-current assets related primarily to workers compensation deposits.

(2) Includes $605.0 million that is included in cash and cash equivalents, $595.4 million included in short-term investments and $5.2 million of restricted cash that is included in other non-current assets related to workers compensation deposits.

Estimated Fair Value Of Short-Term Investments By Contractual Maturity

The estimated fair value of short-term investments by contractual maturity as of September 30, 2014 is as follows:

	(in thousands)
Due within one year	$	112,361
Due after one year and through 5 years	371,241
Total short-term investments	$	483,602