Investments

6 Months Ended

Jun. 30, 2021

Debt Securities, Available-for-sale [Abstract]

Marketable Debt Securities

The following is a summary of our available-for-sale debt securities recorded within short-term and long-term investments on the condensed consolidated balance sheets (in millions):


	June 30, 2021
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-sale securities:
Commercial paper	$	430	$	—	$	—	$	430
Corporate notes and bonds	2,324		5		(1)		2,328
Certificates of deposit	61		—		—		61
U.S. government and agency securities	107		—		—		107
Mortgage and asset backed securities	47		—		(1)		46

Total available-for-sale securities	$	2,969	$	5	$	(2)	$	2,972


	December 31, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-sale securities:
Commercial paper	$	406	$	—	$	—	$	406
Corporate notes and bonds	2,298		10		—		2,308
Certificates of deposit	23		—		—		23
U.S. government and agency securities	145		1		—		146
Total available-for-sale securities	$	2,872	$	11	$	—	$	2,883

As of June 30, 2021, the contractual maturities of our available-for-sale debt securities, excluding those securities classified within cash and cash equivalents on the condensed consolidated balance sheet and mortgage and asset backed securities that do not have a single maturity, did not exceed 36 months. The fair values of available-for-sale securities, by remaining contractual maturity, are as follows (in millions):


	June 30, 2021
Due within 1 year	$	1,622
Due in 1 year through 5 years	1,304
Instruments not due in single maturity	46
Total	$	2,972

As of June 30, 2021 and December 31, 2020, the gross unrealized losses that have been in a continuous unrealized loss position related to $875 million and $637 million available-for-sale debt securities, respectively, were not material.

The decline in fair value below amortized cost basis was not considered other than temporary as it is more likely than not we will hold the securities until maturity or a recovery of the cost basis, and credit-related impairment losses were not deemed material as of June 30, 2021.

Strategic Investments

As of June 30, 2021 and December 31, 2020, the total amount of equity investments in privately-held companies included in other assets on our condensed consolidated balance sheets was $44 million and $28 million, respectively. We classify these assets as Level 3 within the fair value hierarchy as only an impairment or observable adjustment is recognized based on observable transaction price at the transaction date of identical or similar investment of the same issuer and other unobservable inputs such as volatility.