AVAILABLE-FOR-SALE DEBT SECURITIES

6 Months Ended

Jun. 30, 2021

Debt Securities, Available-for-sale [Abstract]

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


	June 30, 2021								December 31, 2020
(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	$	413	$	—	$	—	$	413	$	308	$	1	$	—	$	309
Certificates of deposit	387		—		—		387		216		—		—		216
Non-U.S. government securities	49		—		—		49		43		—		—		43
Corporate debt securities	1,262		1		(1)		1,262		1,140		2		—		1,142
Residential mortgage and asset-backed securities	412		—		—		412		316		—		—		316
Total	$	2,523	$	1	$	(1)	$	2,523	$	2,023	$	3	$	—	$	2,026

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


(in millions)	June 30, 2021		December 31, 2020
Cash and cash equivalents	$	55	$	113
Short-term marketable securities	1,632		1,411
Long-term marketable securities	836		502
Total	$	2,523	$	2,026

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


	June 30, 2021
(in millions)	Amortized Cost		Fair Value
Within one year	$	1,687	$	1,687
After one year through five years	814		814
After five years	22		22
Total	$	2,523	$	2,523

We held a total of 226 positions which were in an unrealized loss position as of June 30, 2021. The unrealized losses were largely due to changes in interest rates. Aggregated gross unrealized losses on available-for-sale debt securities were not material. No impairment was recognized for the three and six months ended June 30, 2021. Gross realized gains and gross realized losses on available-for-sale debt securities were not material for the three and six months ended June 30, 2021.