Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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Financial Assets and Liabilities - Fair Value Measurements (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Financial assets and financial liabilities measured at fair value on a recurring basis:
Impairments of non-financial assets	$ 0	$ 0	$ 0	$ 0
Prepaid expenses and other current assets
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	$ 4		$ 4		$ 0