Investments (Tables)

9 Months Ended

Sep. 30, 2019

Investments [Abstract]

Fair value of short and long-term investments classified as available for sale

The following tables summarize the unrealized gains and losses and estimated fair value of our investments classified as available-for-sale as of September 30, 2019 and December 31, 2018 (in millions):

	September 30, 2019
	Gross Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Short-term investments:
Restricted cash	$	12	$	—	$	—		$	12
Corporate debt securities	2,176		1		—			2,177
	$	2,188	$	1	$	—		$	2,189
Long-term investments:
Corporate debt securities	1,134		3		(1		)	1,136
	$	1,134	$	3	$	(1	)	$	1,136

	December 31, 2018
	Gross Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Short-term investments:
Restricted cash	$	17	$	—	$	—		$	17
Corporate debt securities	2,615		—		(9		)	2,606
Government and agency securities	90		—		—			90
	$	2,722	$	—	$	(9	)	$	2,713
Long-term investments:
Corporate debt securities	3,682		1		(48		)	3,635
	$	3,682	$	1	$	(48	)	$	3,635

Estimated fair values of short and long-term investments classified by date of contractual maturity

The estimated fair values of our short-term and long-term investments classified as available-for-sale by date of contractual maturity as of September 30, 2019 are as follows (in millions):  

	September 30, 2019
One year or less (including restricted cash of $12)	$	2,189
One year through two years	748
Two years through three years	301
Three years through four years	87
	$	3,325

Schedule of equity method investments

The following table provides a summary of our equity investments as of September 30, 2019 and December 31, 2018 (in millions):

	September 30, 2019		December 31, 2018
Equity investments without readily determinable fair values	$	293	$	137
Equity investments under the equity method of accounting	17		6
Total equity investments	$	310	$	143

Schedule of equity securities without readily determinable fair value

The following table summarizes the change in total carrying value during the three and nine months ended September 30, 2019 and 2018 related to equity investments without readily determinable fair values still held at September 30, 2019 and 2018 (in millions):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Carrying value, beginning of period	$	136		$	859		$	137		$	872
Additions	160			—			160			23
Sales	—			(718		)	—			(718		)
Downward adjustments for observable price changes and impairment	—			—			—			(20		)
Foreign currency translation and other	(3		)	(3		)	(4		)	(19		)
Carrying value, end of period	$	293		$	138		$	293		$	138