Investments (Tables)

12 Months Ended

Dec. 31, 2020

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 December 31, 2020 and 2019 (in millions):

	December 31, 2020
	Gross Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Short-term investments:
Restricted cash	$	143	$	—	$	—	$	143
Corporate debt securities	2,252		3		—		2,255
	$	2,395	$	3	$	—	$	2,398
Long-term investments:
Corporate debt securities	284		2		—		286
	$	284	$	2	$	—	$	286

	December 31, 2019
	Gross Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Short-term investments:
Restricted cash	$	21	$	—	$	—	$	21
Corporate debt securities	1,653		1		—		1,654
Government and agency securities	175		—		—		175
	$	1,849	$	1	$	—	$	1,850
Long-term investments:
Corporate debt securities	957		4		—		961
	$	957	$	4	$	—	$	961

Estimated fair values of short and long-term investments classified as available for sale by date of contractual maturity

The estimated fair values of our short-term and long-term investments classified as available-for-sale and restricted cash by date of contractual maturity as of December 31, 2020 are as follows (in millions): 

	December 31, 2020
One year or less (including restricted cash of $143)	$	2,398
One year through two years	198
Two years through three years	88
Total	$	2,684

Schedule of equity investments

The following table provides a summary of our equity investments (in millions):

	December 31, 2020		December 31, 2019
Equity investments without readily determinable fair values	$	539	$	307
Equity investments under the equity method of accounting	8		7
Total equity investments	$	547	$	314

Summary of unrealized gains and losses on equity investments held

The following table provides a summary of unrealized gains and losses recorded in interest and other, net during the twelve months ended December 31, 2020 related to equity investments held at December 31, 2020.

	Year Ended December 31, 2020
Net gains/(losses) recognized during the period on equity investments	$	240
Less: Net gains/(losses) recognized during the period on equity investments sold during the period	—
Total unrealized gains/(losses) on equity investments still held at December 31, 2020	$	240

Schedule of investments without readily determinable fair value

The following table summarizes the total carrying value of equity investments without readily determinable fair values still held (in millions):

	Year Ended December 31, 2020		Year Ended December 31, 2019
Carrying value, beginning of period	$	307	$	107
Additions	22		200
Upward adjustments for observable price changes	239		—
Downward adjustments for observable price changes and impairment	(40)		—
Foreign currency translation and other	11		—
Carrying value, end of period	$	539	$	307