Summary of Significant Accounting Policies and Recent Accounting Pronouncements - Narrative (Details) connection in Millions, $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($) segment unit asset_group connection	Dec. 31, 2023 USD ($) unit	Dec. 31, 2022 USD ($)	Jun. 30, 2024 unit	May 04, 1988
Basis of presentation
Number of connections | connection		4.4
Change in reportable segments		During the second quarter of 2024, UScellular modified its reporting structure due to the planned disposal of its wireless operations and, as a result, disaggregated its operations into two reportable segments – Wireless and Towers. This presentation reflects how UScellular's chief operating decision maker allocates resources and evaluates operating performance following this strategic shift. Prior periods have been updated to conform to the new reportable segments. See Note 19 — Business Segment Information for additional information about UScellular's segments.
Number of reportable segments | segment		2
FCC Licenses, period of renewal		12 years
FCC Licenses, number of accounting units | unit		12	1		2
Loss on impairment of licenses	$ 136	$ 136	$ 0	$ 3
Asset groups | asset_group		2
Agent liability		$ 44	50
Advertising costs		182	181	171
Amortization of implementation costs		$ 19	17	18
Minimum
Basis of presentation
FCC Licenses, period of renewal		10 years
Amortization period		3 years
Maximum
Basis of presentation
FCC Licenses, period of renewal		15 years
Amortization period		5 years
Leasehold and land improvements | Minimum
Basis of presentation
Useful life		1 year
Leasehold and land improvements | Maximum
Basis of presentation
Useful life		30 years
Pension
Basis of presentation
Defined contribution cost		$ 12	11	12
401(k)
Basis of presentation
Defined contribution cost		15	15	$ 15
TDS
Basis of presentation
Income taxes receivable		$ 0	$ 0
UScellular | TDS
Basis of presentation
TDS ownership of UScellular		83.00%
UScellular | TDS | Minimum
Basis of presentation
TDS ownership of UScellular						90.00%