Business Acquisitions - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018
Other acquisitions
Business Acquisition [Line Items]
Payments to acquire businesses, net of cash acquired	$ 62	$ 39

The cash outflow associated with the acquisition of a business, net of the cash acquired from the purchase.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3213-108585

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration