Available-for-Sale Debt Securities

9 Months Ended

Sep. 30, 2020

Debt Securities, Available-for-sale [Abstract]

Available-for-Sale Debt Securities

AVAILABLE-FOR-SALE DEBT SECURITIES

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

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

Accrued interest receivable excluded from both the fair value and amortized cost basis of the available-for-sale debt securities was $49 million and $37 million as of September 30, 2020 and December 31, 2019, respectively, and is recorded in Prepaid and other current assets on our Condensed Consolidated Balance Sheets. There were no write-offs of accrued interest receivable during the three and nine months ended September 30, 2020.

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

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

We held a total of 208 positions which were in an unrealized loss position as of September 30, 2020. The unrealized losses are largely due to changes in interest rates. Aggregated gross unrealized losses on available-for-sale corporate debt securities were not material, and accordingly, no impairments were recognized for the three and nine months ended September 30, 2020.