Available-for-Sale Debt Securities

12 Months Ended

Dec. 31, 2020

Debt Securities, Available-for-sale [Abstract]

AVAILABLE-FOR-SALE DEBT SECURITIES

The following table summarizes our available-for-sale debt securities:


	December 31, 2020								December 31, 2019
(in millions)	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	$	308	$	1	$	—	$	309	$	2,433	$	—	$	—	$	2,433
Certificates of deposit	216		—		—		216		3,517		—		—		3,517
U.S. government agencies securities	—		—		—		—		1,081		—		—		1,081
Non-U.S. government securities	43		—		—		43		174		—		—		174
Corporate debt securities	1,140		2		—		1,142		9,203		2		(1)		9,204
Residential mortgage and asset-backed securities	316		—		—		316		91		—		—		91
Total	$	2,023	$	3	$	—	$	2,026	$	16,499	$	2	$	(1)	$	16,500

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


(in millions)	December 31, 2020		December 31, 2019
Cash and cash equivalents	$	113	$	2,291
Short-term marketable securities	1,411		12,721
Long-term marketable securities	502		1,488
Total	$	2,026	$	16,500

Accrued interest receivable excluded from both the fair value and amortized cost basis of the available-for-sale debt securities was $9 million and $37 million as of December 31, 2020 and 2019, respectively, and is recorded in Prepaid and other current assets on our Consolidated Balance Sheets. There were no write-offs of accrued interest receivable during the years ended December 31, 2020 and 2019.

The following table summarizes our available-for-sale debt securities by contractual maturity:


	December 31, 2020
(in millions)	Amortized Cost		Fair Value
Within one year	$	1,522	$	1,524
After one year through five years	489		490
After five years	12		12
Total	$	2,023	$	2,026

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


	Less Than 12 Months				12 Months or Greater				Total
(in millions)	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

We held a total of 75 and 305 positions which were in an unrealized loss position as of December 31, 2020 and 2019, respectively. Aggregated gross unrealized losses on available-for-sale corporate debt securities were not material, and accordingly, no impairments were recognized for the years ended December 31, 2020 and 2019. Gross realized gains and gross realized losses on available-for-sale debt securities were not material for the years ended December 31, 2020 and 2019.