Cash, Cash Equivalents, and Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2014

Investments, Debt and Equity Securities [Abstract]

The following table summarizes, by major security type, our cash, cash equivalents, and marketable securities that are measured at fair value on a recurring basis and are categorized using the fair value hierarchy (in millions):



	March 31, 2014										December 31, 2013
	Cost or Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Total Estimated Fair Value			Total Estimated Fair Value
Cash	$	2,902	$	—	$	—		$	2,902		$	3,008
Level 1 securities:
Money market funds	2,490		—		—			2,490			5,914
Equity securities	3		—		—			3			4
Level 2 securities:
Foreign government and agency securities	617		2		(1		)	618			758
U.S. government and agency securities	2,128		2		(2		)	2,128			2,222
Corporate debt securities	755		3		—			758			741
Asset-backed securities	69		—		—			69			65
Other fixed income securities	34		—		—			34			36
	$	8,998	$	7	$	(3	)	$	9,002		$	12,748
Less: Restricted cash, cash equivalents, and marketable securities (1)								(336		)	(301		)
Total cash, cash equivalents, and marketable securities								$	8,666		$	12,447

___________________

(1)

We are required to pledge or otherwise restrict a portion of our cash, cash equivalents, and marketable securities as collateral for standby and trade letters of credit, guarantees, debt, and real estate lease agreements. We classify cash and marketable securities with use restrictions of less than twelve months as “Accounts receivable, net and other” and of twelve months or longer as non-current “Other assets” on our consolidated balance sheets. See “Note 3 — Commitments and Contingencies.”

Investments Classified by Contractual Maturity Date

The following table summarizes the contractual maturities of our cash equivalent and marketable fixed-income securities as of March 31, 2014 (in millions):



	Amortized Cost		Estimated Fair Value
Due within one year	$	3,951	$	3,953
Due after one year through five years	1,781		1,784
Due after five years through ten years	129		129
Due after ten years	232		231
	$	6,093	$	6,097