Fair Value Disclosures (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Derivative Asset [Abstract]
Derivative assets	$ 193	$ 17
Liabilities
Derivative liabilities	121	18
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at January 1	0
Merger impact	28
Gains (losses) recognized in earnings	2
Balance at December 31	30
Fair Value Additional Information [Abstract]
Carrying value of long-term debt	13,811	8,762
Level 1 \| Fair Value, Measurements, Recurring
Derivative Asset [Abstract]
Derivative assets	0	0
Investments and securities	22
Total	22
Liabilities
Derivative liabilities	0	0
Level 2
Fair Value Additional Information [Abstract]
Fair value of long-term debt	13,725	8,969
Level 2 \| Fair Value, Measurements, Recurring
Derivative Asset [Abstract]
Derivative assets	193	17
Total	193	17
Liabilities
Derivative liabilities	121	18
Level 3 \| Fair Value, Measurements, Recurring
Derivative Asset [Abstract]
Derivative assets	0	0
Investments and securities	30
Total	30
Liabilities
Derivative liabilities	$ 0	$ 0

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Fair Value, Measurement With Unobservable Inputs Reconciliation, Business Combination

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Fair value, before effects of master netting arrangements, of a financial asset or other 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. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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