Short-term Investments (Tables)

3 Months Ended

Mar. 31, 2015

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 and where they are classified on the Consolidated Balance Sheets:

	As of March 31, 2015
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
Cash	$	2,354,639	$	—	$	—		$	2,354,639
Level 1 securities:
Money market funds	105,060		—		—			105,060
Level 2 securities:
Corporate debt securities	270,196		726		(49		)	270,873
Government securities	198,815		479		(5		)	199,289
Certificate of deposits and commercial paper	6,100		—		—			6,100
Agency securities	26,644		25		—			26,669
Total	$	2,961,454	$	1,230	$	(54	)	$	2,962,630

	As of December 31, 2014
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
Cash	$	1,007,543	$	—	$	—		$	1,007,543
Level 1 securities:
Money market funds	111,759		—		—			111,759
Level 2 securities:
Corporate debt securities	295,500		432		(199		)	295,733
Government securities	168,749		120		(95		)	168,774
Asset and mortgage-backed securities	112		—		—			112
Certificate of deposits	3,600		—		—			3,600
Agency securities	26,665		5		(1		)	26,669
Total	$	1,613,928	$	557	$	(295	)	$	1,614,190

	As of
	March 31, 2015		December 31, 2014
	(in thousands)
Cash and cash equivalents	$	2,454,777	$	1,113,608
Short-term investments	502,931		494,888
Other non-current assets (1)	4,922		5,694
Total	$	2,962,630	$	1,614,190

(1) Primarily restricted cash that is 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 March 31, 2015 is as follows:

	(in thousands)
Due within one year	$	168,017
Due after one year and through five years	334,914
Total short-term investments	$	502,931