Restructuring and Integration Costs and Transaction Costs - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Restructuring And Related Activities [Abstract]
Restructuring and integration costs	$ 20	$ 63	$ 89	$ 75
Transaction costs	$ 11	$ 37	$ 15	$ 40

A fee charged for services from professionals such as doctors, lawyers and accountants. The term is often expanded to include other professions, for example, pharmacists charging to maintain a medicinal profile of a client or customer.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07.2(a),(b),(c),(d))
-URI http://asc.fasb.org/extlink&oid=114873854&loc=SL114874292-224272

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 220
-Section 45
-Paragraph 3
-Subparagraph (k)
-URI http://asc.fasb.org/extlink&oid=114873831&loc=SL114874205-224268

Name:	us-gaap_ProfessionalFees
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration