Fair Value (Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in equity securities	$ 137	$ 137
Available-for-sale securities	100	93
Trading securities	12	11
Fair value of interest rate swap agreements		3
Total assets	249	244
Fair value of interest rate swap agreements	3	2
Total liabilities	3	2
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in equity securities	137	137
Total assets	137	137
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	100	93
Trading securities	12	11
Fair value of interest rate swap agreements		3
Total assets	112	107
Fair value of interest rate swap agreements	3	2
Total liabilities	$ 3	$ 2

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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Amount of 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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Fair value, after the 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 not subject to a master netting arrangement and not elected to be offset.

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Fair value of financial and nonfinancial obligations.

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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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