Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Disaggregation of revenue
Revenue from contracts with customers	$ 1,206	$ 1,235	$ 2,436	$ 2,508
Operating lease income	32	32	64	62
Total operating revenues	1,238	1,267	2,500	2,570
Transferred over time
Disaggregation of revenue
Revenue from contracts with customers	1,002	1,009	2,014	2,022
Transferred over time \| Retail service
Disaggregation of revenue
Revenue from contracts with customers	666	686	1,344	1,378
Transferred over time \| Residential
Disaggregation of revenue
Revenue from contracts with customers	186	175	372	344
Transferred over time \| Commercial
Disaggregation of revenue
Revenue from contracts with customers	37	39	74	80
Transferred over time \| Wholesale
Disaggregation of revenue
Revenue from contracts with customers	43	42	86	84
Transferred over time \| Other service
Disaggregation of revenue
Revenue from contracts with customers	70	67	138	136
Transferred at point in time \| Equipment and product sales
Disaggregation of revenue
Revenue from contracts with customers	204	226	422	486
UScellular
Disaggregation of revenue
Revenue from contracts with customers	902	932	1,826	1,892
Operating lease income	25	25	51	50
Total operating revenues	927	957	1,877	1,942
UScellular \| Transferred over time
Disaggregation of revenue
Revenue from contracts with customers	718	735	1,446	1,477
UScellular \| Transferred over time \| Retail service
Disaggregation of revenue
Revenue from contracts with customers	666	686	1,344	1,378
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	52	49	102	99
UScellular \| Transferred at point in time \| Equipment and product sales
Disaggregation of revenue
Revenue from contracts with customers	184	197	380	415
TDS Telecom
Disaggregation of revenue
Revenue from contracts with customers	266	256	532	508
Operating lease income	1	1	2	2
Total operating revenues	267	257	534	510
TDS Telecom \| Transferred over time
Disaggregation of revenue
Revenue from contracts with customers	266	256	532	508
TDS Telecom \| Transferred over time \| Retail service
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	186	175	372	344
TDS Telecom \| Transferred over time \| Commercial
Disaggregation of revenue
Revenue from contracts with customers	37	39	74	80
TDS Telecom \| Transferred over time \| Wholesale
Disaggregation of revenue
Revenue from contracts with customers	43	42	86	84
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	0	0
Corporate, Eliminations and Other
Disaggregation of revenue
Revenue from contracts with customers	38	47	78	108
Operating lease income	6	6	11	10
Total operating revenues	44	53	89	118
Corporate, Eliminations and Other \| Transferred over time
Disaggregation of revenue
Revenue from contracts with customers	18	18	36	37
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 \| 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	18	18	36	37
Corporate, Eliminations and Other \| Transferred at point in time \| Equipment and product sales
Disaggregation of revenue
Revenue from contracts with customers	$ 20	$ 29	$ 42	$ 71