Cash, Cash Equivalents, and Marketable Securities (Tables)

6 Months Ended

Jun. 30, 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			June 30, 2018
	Total Estimated Fair Value			Cost or Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Total Estimated Fair Value
Cash	$	9,982		$	8,107	$	—	$	—		$	8,107
Level 1 securities:
Money market funds	11,343			10,094		—		—			10,094
Equity securities	53			25		83		—			108
Level 2 securities:
Foreign government and agency securities	620			389		—		—			389
U.S. government and agency securities	4,823			5,465		1		(25		)	5,441
Corporate debt securities	4,257			2,638		1		(18		)	2,621
Asset-backed securities	905			756		—		(8		)	748
Other fixed income securities	338			225		—		(2		)	223
Equity securities	—			29		6		—			35
	$	32,321		$	27,728	$	91	$	(53	)	$	27,766
Less: Restricted cash, cash equivalents, and marketable securities (1)	(1,335		)								(716		)
Total cash, cash equivalents, and marketable securities	$	30,986									$	27,050

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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 remaining contractual maturities of our cash equivalents and marketable fixed-income securities as of June 30, 2018 (in millions):

	Amortized Cost		Estimated Fair Value
Due within one year	$	16,023	$	16,016
Due after one year through five years	2,895		2,864
Due after five years through ten years	216		212
Due after ten years	433		424
Total	$	19,567	$	19,516

Actual maturities may differ from the contractual maturities because borrowers may have certain prepayment conditions.

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		June 30, 2018
Cash and cash equivalents	$	20,522	$	19,823
Restricted cash included in accounts receivable, net and other	1,329		707
Restricted cash included in other assets	5		6
Total cash, cash equivalents, and restricted cash shown in the consolidated statements of cash flows	$	21,856	$	20,536