Available-for-Sale Debt Securities (Tables)

12 Months Ended

Dec. 31, 2019

Debt Securities, Available-for-sale [Abstract]

Summary of Available-for-Sale Debt Securities at Estimated Fair Value

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

	December 31, 2019									December 31, 2018
	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	$	2,433	$	—	$	—		$	2,433	$	3,978	$	—	$	(9	)	$	3,969
Certificates of deposit	3,517		—		—			3,517		4,361		—		—			4,361
U.S. government agencies securities	1,081		—		—			1,081		943		—		(5		)	938
Non-U.S. government securities	174		—		—			174		307		—		(2		)	305
Corporate debt securities	9,203		2		(1		)	9,204		13,095		1		(29		)	13,067
Residential mortgage and asset-backed securities	91		—		—			91		1,532		—		(8		)	1,524
Total	$	16,499	$	2	$	(1	)	$	16,500	$	24,216	$	1	$	(53	)	$	24,164

Summary of the Classification of Available-for-Sale Debt Securities

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

	December 31, 2019		December 31, 2018
Cash and cash equivalents	$	2,291	$	10,592
Short-term marketable securities	12,721		12,149
Long-term marketable securities	1,488		1,423
Total	$	16,500	$	24,164

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):

	December 31, 2019
	Amortized Cost		Fair Value
Within one year	$	15,011	$	15,012
After one year through five years	1,465		1,465
After five years	23		23
Total	$	16,499	$	16,500

Summary of Available-for-Sale Debt Securities in a Continuous Loss Position Deemed not to be Other-than-Temporarily Impaired

The following table summarizes our available-for-sale debt securities that were in a continuous unrealized loss position, but were not deemed to be other-than-temporarily impaired (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
December 31, 2019
Corporate debt securities	$	(1	)	$	1,866	$	—		$	4	$	(1	)	$	1,870
December 31, 2018
U.S. treasury securities	$	—		$	896	$	(9	)	$	1,383	$	(9	)	$	2,279
U.S. government agencies securities	—			30		(5		)	553		(5		)	583
Non-U.S. government securities	—			86		(2		)	192		(2		)	278
Corporate debt securities	(1		)	1,600		(28		)	4,204		(29		)	5,804
Residential mortgage and asset-backed securities	—			192		(8		)	1,186		(8		)	1,378
Total	$	(1	)	$	2,804	$	(52	)	$	7,518	$	(53	)	$	10,322