Restructuring and Asset Impairment Charges (Narrative) (Details)	3 Months Ended	9 Months Ended
Sep. 30, 2021 USD ($) restructuring_program	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) restructuring_program	Sep. 30, 2020 USD ($)
Restructuring Cost and Reserve
Restructuring costs incurred to date	$ 17,000,000		$ 17,000,000
Asset impairment charges	$ 0	$ 10,000,000	$ 0	$ 36,000,000
Closed Restructuring Programs
Restructuring Cost and Reserve
Number of restructuring programs \| restructuring_program	5		5
Restructuring costs incurred to date	$ 351,000,000		$ 351,000,000
Restructuring and related activities, number of completed restructuring programs, liability	$ 11,000,000		$ 11,000,000

Restructuring and Related Activities, Number of Completed Restructuring Programs

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- Definition

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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- Definition

Amount of costs incurred to date for the specified restructuring cost.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Carrying amount (including both current and noncurrent portions of the accrual) as of the balance sheet date pertaining to a specified type of cost associated with exit from or disposal of business activities or restructuring pursuant to a duly authorized plan.

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