Derivative Instruments - Additional Information (Details) - USD ($)	9 Months Ended
Sep. 30, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Maximum maturity of foreign currency exchange contracts	18 months
Net derivative gains related to cash flow hedges to be reclassified into earnings within the next 12 months	$ 122,000,000
Derivative asset, offset	18,000,000	$ 56,000,000
Cash collateral posted related to derivative liabilities	1,000,000	38,000,000
Offsetting Liabilities [Line Items]
Counterparty cash collateral		$ 0
Other current liabilities
Offsetting Liabilities [Line Items]
Counterparty cash collateral	135,000,000
Debt securities
Offsetting Liabilities [Line Items]
Counterparty non-cash collateral	$ 3,000,000

Amount of obligation to return cash collateral under master netting arrangements that have not been offset against derivative assets.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 13
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-Section 50
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-Name Accounting Standards Codification
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Amount of right to receive cash collateral under master netting arrangements that have not been offset against derivative liabilities.

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Fair value of asset associated with financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Section 50
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The estimated net amount of unrealized gains or losses on foreign currency cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

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Maximum amount of time remaining before foreign currency exchange rate derivatives mature or expire, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of obligation to return cash collateral under master netting arrangements that have not been offset against securities borrowed.

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