Available-for-Sale Debt Securities (Tables)

9 Months Ended

Sep. 30, 2020

Debt Securities, Available-for-sale [Abstract]

Reconciliation of Available-for-Sale Debt Securities from Cost Basis to Fair Value

The following table summarizes our available-for-sale debt securities (in millions):

	September 30, 2020								December 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
U.S. treasury securities	$	2,225	$	13	$	—	$	2,238	$	2,433	$	—	$	—	$	2,433
Certificates of deposit	2,136		—		—		2,136		3,517		—		—		3,517
U.S. government agencies securities	71		—		—		71		1,081		—		—		1,081
Non-U.S. government securities	220		—		—		220		174		—		—		174
Corporate debt securities	7,506		20		(1)		7,525		9,203		2		(1)		9,204
Residential mortgage and asset-backed securities	1,207		2		—		1,209		91		—		—		91
Total	$	13,365	$	35	$	(1)	$	13,399	$	16,499	$	2	$	(1)	$	16,500

Summary of Classification of Available-for-Sale Debt Securities

The following table summarizes the classification of our available-for-sale debt securities in our Condensed Consolidated Balance Sheets (in millions):

	September 30, 2020		December 31, 2019
Cash and cash equivalents	$	236	$	2,291
Short-term marketable securities	11,089		12,721
Long-term marketable securities	2,074		1,488
Total	$	13,399	$	16,500

Summary of Available-for-Sale Debt Securities by Contractual Maturity

The following table summarizes our available-for-sale debt securities by contractual maturity (in millions):

	September 30, 2020
	Amortized Cost		Fair Value
Within one year	$	11,292	$	11,325
After one year through five years	1,991		1,992
After five years	82		82
Total	$	13,365	$	13,399

Summary of Available-for-Sale Debt Securities in a Continuous Loss Position

The following table summarizes our available-for-sale debt securities in an unrealized loss position (in millions):

	Less Than 12 Months				12 Months or Greater				Total
	Gross Unrealized Losses		Estimated Fair Value		Gross Unrealized Losses		Estimated Fair Value		Gross Unrealized Losses		Estimated Fair Value
September 30, 2020
Corporate debt securities	$	(1)	$	1,042	$	—	$	—	$	(1)	$	1,042
December 31, 2019
Corporate debt securities	$	(1)	$	1,866	$	—	$	4	$	(1)	$	1,870