Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Name:	us-gaap_RestructuringCharges
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Restructuring Charges (Detail) - USD ($) $ in Millions	12 Months Ended
Restructuring Charges (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 53	$ 21	$ 389
General and Administrative Expense [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges			192
Other Income (Expense) [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 197
Retirement Benefits [Member] \| General and Administrative Expense [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 21