Net purchase price.

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Transactions.

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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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Amount of assets held-for-sale that are not part of a disposal group.

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This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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The amount of identifiable intangible assets recognized as of the acquisition date.

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Amount of gain (loss) from sale and disposal of integrated set of activities and assets capable of being conducted and managed for purpose of providing return in form of dividend, lower cost, or other economic benefit to investor, owner, member and participant.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount classified as liabilities attributable to disposal group held for sale or disposed of.

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The number of businesses acquired by the entity during the period.

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Transactions - Additional Information (Detail)	12 Months Ended
Transactions - Additional Information (Detail)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($) Acquisition	Dec. 31, 2018 USD ($)
Transactions [Line Items]
Assets held-for-sale		$ 34,000,000
Asset impairment charges	$ 321,000,000	128,000,000
Goodwill	0	$ 245,000,000	$ 314,000,000
Two Acquisitions [Member]
Transactions [Line Items]
Number of acquisitions \| Acquisition		2
Purchase price consideration		$ 8,000,000
Goodwill		6,000,000
Intangible assets		2,000,000
Maximum [Member] \| Two Acquisitions [Member]
Transactions [Line Items]
Acquisition related costs		1,000,000
Impairment charges [Member]
Transactions [Line Items]
Loss on sale of business	$ (1,000,000)
Held-for-Sale [Member]
Transactions [Line Items]
Assets held-for-sale		34,000,000
Liabilities held-for-sale		6,000,000
Asset impairment charges		$ 9,000,000