Basis of Presentation - Revenue (Detail) $ in Millions	6 Months Ended
Jun. 30, 2018 USD ($) segment	Jan. 01, 2018 USD ($)	Dec. 31, 2017 USD ($)
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Number of areas \| segment	17
Retained earnings	$ 9,166		$ 8,588
Contract acquisition costs	139
Deferred income taxes	$ 1,250		$ 1,248
Revenue, Practical Expedient, Remaining Performance Obligation [true/false]	true
Accounting Standards Update 2014-09 [Member] \| Impact of adoption [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Retained earnings		$ 80
Contract acquisition costs		108
Deferred income taxes		$ 28

Amount, after accumulated amortization and accumulated impairment loss, of asset recognized from cost incurred to obtain or fulfill contract with customer.

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