Net purchase price.

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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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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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Acquisitions - Additional Information (Detail) $ in Millions	3 Months Ended	9 Months Ended
	Jun. 30, 2019 USD ($) Acquisition	Sep. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
Business Acquisition [Line Items]
Goodwill		$ 320	$ 314
Two Acquisitions [Member]
Business Acquisition [Line Items]
Number of acquisitions \| Acquisition	2
Purchase price consideration	$ 8
Goodwill	6
Intangible assets	$ 2
Two Acquisitions [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Acquisition related costs		$ 1