Cash, Cash Equivalents, and Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Fair Value by Major Security Type

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

	December 31, 2017			March 31, 2018
	Total Estimated Fair Value			Cost or Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Total Estimated Fair Value
Cash	$	9,982		$	8,706	$	—	$	—		$	8,706
Level 1 securities:
Money market funds	11,343			8,663		—		—			8,663
Equity securities	53			23		54		—			77
Level 2 securities:
Foreign government and agency securities	620			421		—		(1		)	420
U.S. government and agency securities	4,823			3,557		1		(25		)	3,533
Corporate debt securities	4,257			3,412		—		(19		)	3,393
Asset-backed securities	905			803		—		(8		)	795
Other fixed income securities	338			285		—		(2		)	283
Equity securities	—			28		5		—			33
	$	32,321		$	25,898	$	60	$	(55	)	$	25,903
Less: Restricted cash, cash equivalents, and marketable securities (1)	(1,335		)								(940		)
Total cash, cash equivalents, and marketable securities	$	30,986									$	24,963

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(1) We are required to pledge or otherwise restrict a portion of our cash, cash equivalents, and marketable securities as collateral for real estate leases, amounts due to third-party sellers in certain jurisdictions, debt, and standby and trade letters of credit. We classify cash, cash equivalents, 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 equivalents and marketable fixed-income securities as of March 31, 2018 (in millions):

	Amortized Cost		Estimated Fair Value
Due within one year	$	12,969	$	12,960
Due after one year through five years	3,434		3,400
Due after five years through ten years	248		245
Due after ten years	490		482
Total	$	17,141	$	17,087

Reconciliation of cash, cash equivalents, and restricted cash [Table Text Block]

The following table provides a reconciliation of the amount of cash, cash equivalents, and restricted cash reported within the consolidated balance sheets to the total of the same such amounts shown in the consolidated statements of cash flows (in millions):

	December 31, 2017		March 31, 2018
Cash and cash equivalents	$	20,522	$	16,676
Restricted cash included in accounts receivable, net and other	1,329		935
Restricted cash included in other assets	5		5
Total cash, cash equivalents, and restricted cash shown in the consolidated statements of cash flows	$	21,856	$	17,616