Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of revenue
Revenue from contracts with customers	$ 1,247	$ 1,362	$ 3,753	$ 3,966
Operating lease income	31	30	95	90
Total operating revenues	1,278	1,392	3,848	4,056
Transferred over time
Disaggregation of revenue
Revenue from contracts with customers	1,012	1,031	3,033	3,096
Transferred over time \| Retail service
Disaggregation of revenue
Revenue from contracts with customers	687	696	2,065	2,098
Transferred over time \| Inbound roaming
Disaggregation of revenue
Revenue from contracts with customers	8	17	25	56
Transferred over time \| Residential
Disaggregation of revenue
Revenue from contracts with customers	177	170	521	500
Transferred over time \| Commercial
Disaggregation of revenue
Revenue from contracts with customers	38	43	118	130
Transferred over time \| Wholesale
Disaggregation of revenue
Revenue from contracts with customers	41	42	125	129
Transferred over time \| Other service
Disaggregation of revenue
Revenue from contracts with customers	61	63	179	183
Transferred at point in time \| Equipment and product sales
Disaggregation of revenue
Revenue from contracts with customers	235	331	720	870
UScellular
Disaggregation of revenue
Revenue from contracts with customers	938	1,060	2,831	3,052
Operating lease income	25	23	75	68
Total operating revenues	963	1,083	2,906	3,120
UScellular \| Transferred over time
Disaggregation of revenue
Revenue from contracts with customers	737	758	2,214	2,283
UScellular \| Transferred over time \| Retail service
Disaggregation of revenue
Revenue from contracts with customers	687	696	2,065	2,098
UScellular \| Transferred over time \| Inbound roaming
Disaggregation of revenue
Revenue from contracts with customers	8	17	25	56
UScellular \| Transferred over time \| Residential
Disaggregation of revenue
Revenue from contracts with customers	0	0	0	0
UScellular \| Transferred over time \| Commercial
Disaggregation of revenue
Revenue from contracts with customers	0	0	0	0
UScellular \| Transferred over time \| Wholesale
Disaggregation of revenue
Revenue from contracts with customers	0	0	0	0
UScellular \| Transferred over time \| Other service
Disaggregation of revenue
Revenue from contracts with customers	42	45	124	129
UScellular \| Transferred at point in time \| Equipment and product sales
Disaggregation of revenue
Revenue from contracts with customers	201	302	617	769
TDS Telecom
Disaggregation of revenue
Revenue from contracts with customers	256	255	764	761
Operating lease income	1	1	3	3
Total operating revenues	256	256	767	763
TDS Telecom \| Transferred over time
Disaggregation of revenue
Revenue from contracts with customers	255	255	763	760
TDS Telecom \| Transferred over time \| Retail service
Disaggregation of revenue
Revenue from contracts with customers	0	0	0	0
TDS Telecom \| Transferred over time \| Inbound roaming
Disaggregation of revenue
Revenue from contracts with customers	0	0	0	0
TDS Telecom \| Transferred over time \| Residential
Disaggregation of revenue
Revenue from contracts with customers	177	170	521	500
TDS Telecom \| Transferred over time \| Commercial
Disaggregation of revenue
Revenue from contracts with customers	38	43	118	130
TDS Telecom \| Transferred over time \| Wholesale
Disaggregation of revenue
Revenue from contracts with customers	41	42	125	129
TDS Telecom \| Transferred over time \| Other service
Disaggregation of revenue
Revenue from contracts with customers	0	0	0	0
TDS Telecom \| Transferred at point in time \| Equipment and product sales
Disaggregation of revenue
Revenue from contracts with customers	0	0	1	1
Corporate, Eliminations and Other
Disaggregation of revenue
Revenue from contracts with customers	53	47	157	154
Operating lease income	5	6	17	19
Total operating revenues	59	53	175	173
Corporate, Eliminations and Other \| Transferred over time
Disaggregation of revenue
Revenue from contracts with customers	19	18	55	54
Corporate, Eliminations and Other \| Transferred over time \| Retail service
Disaggregation of revenue
Revenue from contracts with customers	0	0	0	0
Corporate, Eliminations and Other \| Transferred over time \| Inbound roaming
Disaggregation of revenue
Revenue from contracts with customers	0	0	0	0
Corporate, Eliminations and Other \| Transferred over time \| Residential
Disaggregation of revenue
Revenue from contracts with customers	0	0	0	0
Corporate, Eliminations and Other \| Transferred over time \| Commercial
Disaggregation of revenue
Revenue from contracts with customers	0	0	0	0
Corporate, Eliminations and Other \| Transferred over time \| Wholesale
Disaggregation of revenue
Revenue from contracts with customers	0	0	0	0
Corporate, Eliminations and Other \| Transferred over time \| Other service
Disaggregation of revenue
Revenue from contracts with customers	19	18	55	54
Corporate, Eliminations and Other \| Transferred at point in time \| Equipment and product sales
Disaggregation of revenue
Revenue from contracts with customers	$ 34	$ 29	$ 102	$ 100