Tower Transaction (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($) tower	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2013 USD ($)
Other Liabilities [Line Items]
Balance of tower assets	$ 128,871	$ 128,489	$ 127,445
Depreciation expense	$ 20,421	18,593	17,852
Crown Castle International
Other Liabilities [Line Items]
Number of wireless towers with exclusive rights to lease | tower	9,048
Number of wireless towers subject to disposition | tower	627
Cash from failed sale-leaseback				$ 4,827
Term of lease	28 years
Approximate fixed future purchase option price on failed sale-leaseback	$ 4,200
Initial term	20 years
Approximate annual interest rate - financing obligation	3.90%
Balance of tower assets	$ 608	647
Depreciation expense	39	$ 39	$ 39
Lease payments	269
Minimum lease payments - 2025	274
Minimum lease payments - 2026	280
Minimum lease payments - 2027	285
Minimum lease payments - 2028	291
Minimum lease payments - 2029	297
Minimum lease payments - thereafter	$ 1,389