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

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The assets recognized for each amount of assets recorded in a transaction with the acquiree that is recognized separately from the acquisition of assets and assumptions of liabilities in the business combination.

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Remaining amortization period of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
	Jun. 01, 2016	Mar. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	May 31, 2017
Business Acquisition [Line Items]
Purchase price consideration	$ 179	$ 179
Goodwill			$ 311	$ 314	$ 328	$ 119
Intangible assets						$ 45
Acquisition related costs			2
Non-Compete [Member]
Business Acquisition [Line Items]
Intangible assets			$ 7
Intangible assets amortization period			2 years