Available-for-Sale Debt Securities (Tables)

3 Months Ended

Mar. 31, 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):



	March 31, 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	$	2,048	$	24	$	—		$	2,072	$	2,433	$	—	$	—		$	2,433
Certificates of deposit	3,201		—		—			3,201		3,517		—		—			3,517
U.S. government agencies securities	134		—		—			134		1,081		—		—			1,081
Non-U.S. government securities	22		—		—			22		174		—		—			174
Corporate debt securities	9,287		3		(55		)	9,235		9,203		2		(1		)	9,204
Residential mortgage and asset-backed securities	260		—		(4		)	256		91		—		—			91
Total	$	14,952	$	27	$	(59	)	$	14,920	$	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):



	March 31, 2020		December 31, 2019
Cash and cash equivalents	$	657	$	2,291
Short-term marketable securities	10,734		12,721
Long-term marketable securities	3,529		1,488
Total	$	14,920	$	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):



	March 31, 2020
	Amortized Cost		Fair Value
Within one year	$	11,420	$	11,391
After one year through five years	3,513		3,510
After five years	19		19
Total	$	14,952	$	14,920

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
March 31, 2020
Corporate debt securities	$	(55	)	$	5,639	$	—	$	—	$	(55	)	$	5,639
Residential mortgage and asset-backed securities	(4		)	229		—		6		(4		)	235
Total	$	(59	)	$	5,868	$	—	$	6	$	(59	)	$	5,874

December 31, 2019
Corporate debt securities	$	(1	)	$	1,866	$	—	$	4	$	(1	)	$	1,870