Long-Term Debt - Additional Information (Details) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Long-term debt, fair value	$ 2,000	$ 2,200
Debt Instrument [Line Items]
Assets	4,275	4,275
Liabilities	$ 3,202	$ 3,441
Sales Revenue, Net \| Non-Guarantor Subsidiaries
Debt Instrument [Line Items]
Concentration risk, percentage	47.80%
Assets, Total \| Non-Guarantor Subsidiaries
Debt Instrument [Line Items]
Concentration risk, percentage	84.00%
Assets	$ 3,600
Liabilities, Total \| Non-Guarantor Subsidiaries
Debt Instrument [Line Items]
Concentration risk, percentage	80.10%
Liabilities	$ 2,600

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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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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Sum of the carrying amounts as of the balance sheet date of all liabilities that are recognized. Liabilities are probable future sacrifices of economic benefits arising from present obligations of an entity to transfer assets or provide services to other entities in the future.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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