Revenue Recognition (Disaggregation Of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 2,009	$ 2,102
Subsidy revenue	92	97
Total revenue	2,101	2,199
Lease revenue	18
Revenue from contracts with customers, performance obligation	5,055
Data And Internet Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	967	985
Voice Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	650	702
Video Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	268	280
Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	124	135
Consumer [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,077	1,128
Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 932	$ 974

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+ References

No definition available.

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- Definition

Amount of lease income from operating, direct financing, and sales-type leases. Includes, but is not limited to, variable lease payments, interest income, profit (loss) recognized at commencement, and lease payments paid and payable to lessor.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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