Summary Of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash	$ 2,149
Cash and cash equivalents	$ 3,298	$ 6,722	$ 3,701	$ 19,223
Estimated economic useful life	21 years 7 months 6 days
Wireless Licenses
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
FCC licenses - typical term (in years)	10 years
Estimated economic useful life	21 years 7 months 6 days
Money Market Funds and Other Cash Equivalents
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash equivalents	$ 1,149
Foreign Jurisdictions
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash equivalents	$ 1,268
Minimum | Software
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Amortization period for capitalized software costs	3 years
Maximum | Software
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Amortization period for capitalized software costs	7 years
Mexico Segment [Member] | Wireless Licenses
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated economic useful life	25 years