Capital Structure - Components of Accumulated Other Comprehensive Loss (Detail) $ in Millions	6 Months Ended
Jun. 30, 2018 USD ($)
Equity [Abstract]
Unrealized gains on available-for-sale securities, beginning balances	$ 7
Unrealized losses on available-for-sale securities, net of income tax benefit	(5)
Unrealized gains on available-for-sale securities, ending balances	2
Foreign currency translation adjustments, beginning balances	(149)
Foreign currency translation adjustments	(22)
Foreign currency translation adjustments, ending balances	(171)
Defined benefit plans, beginning balances	(168)
Defined benefit plans, (income) expense reclassified into operations from other comprehensive income	7
Defined benefit plans, ending balances	(161)
Change in fair value of derivative instruments, beginning balances	32
Change in fair value of derivative instruments net of income taxes	39
Change in fair value of derivative instruments, ending balances	69
Accumulated other comprehensive income, net of tax, beginning balances	(278)
Unrealized losses on available-for-sale securities, net of income tax benefit	(5)
Foreign currency translation adjustments	(22)
Change in fair value of derivative instruments	39
Expense (income) reclassified into operations from other comprehensive income, Total	5
Accumulated other comprehensive income (loss), net of tax, ending balances	$ (261)

Accumulated unrealized gain (loss), after tax, on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Accumulated change, net of tax, in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Includes an entity's share of an equity investee's Increase or Decrease in deferred hedging gains or losses.

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Amount, after tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

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Accumulated adjustment, net of tax, that results from the process of translating subsidiary financial statements and foreign equity investments into the reporting currency from the functional currency of the reporting entity, net of reclassification of realized foreign currency translation gains or losses.

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Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount, after tax, of reclassification adjustment from accumulated other comprehensive (income) loss for net periodic benefit cost (credit) of defined benefit plan.

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Amount after tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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Amount after tax, before reclassification adjustments, of unrealized holding gain (loss) on available-for-sale securities.

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Amount after tax of reclassification adjustments of other comprehensive income (loss).

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