Property, Plant, and Equipment (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
Jan. 31, 2019	Mar. 31, 2020
Towers [Member]
Property, Plant and Equipment [Line Items]
Proceeds from sale of property	$ 76
Aggregate carrying value	1
Gain on sale of property	$ 75
Accounting Standards Update 2016-02 [Member]
Property, Plant and Equipment [Line Items]
Cumulative-effect adjustment, Net of tax		$ 15
Cumulative-effect adjustment		$ 11

Property, Plant, and Equipment, Carrying Value

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Amount of the cumulative effect on retained earnings before related income tax effect.

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-Topic 250
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Amount of the cumulative effect on retained earnings net of related income tax effect.

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Amount of gain (loss) on sale or disposal of property, plant and equipment assets, including oil and gas property and timber property.

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The cash inflow from the sale of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale.

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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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