Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of revenue
Revenue from contracts with customers	$ 1,286	$ 1,292
Operating lease income	29	26
Total operating revenues	1,315	1,318
Transferred over time
Disaggregation of revenue
Revenue from contracts with customers	1,033	1,016
Transferred over time | Retail service
Disaggregation of revenue
Revenue from contracts with customers	702	683
Transferred over time | Inbound roaming
Disaggregation of revenue
Revenue from contracts with customers	21	28
Transferred over time | Residential
Disaggregation of revenue
Revenue from contracts with customers	163	157
Transferred over time | Commercial
Disaggregation of revenue
Revenue from contracts with customers	44	47
Transferred over time | Wholesale
Disaggregation of revenue
Revenue from contracts with customers	44	45
Transferred over time | Other service
Disaggregation of revenue
Revenue from contracts with customers	59	56
Transferred at point in time | Equipment and product sales
Disaggregation of revenue
Revenue from contracts with customers	253	276
UScellular
Disaggregation of revenue
Revenue from contracts with customers	988	1,003
Operating lease income	22	20
Total operating revenues	1,010	1,023
UScellular | Transferred over time
Disaggregation of revenue
Revenue from contracts with customers	765	751
UScellular | Transferred over time | Retail service
Disaggregation of revenue
Revenue from contracts with customers	702	683
UScellular | Transferred over time | Retail service | Prior period reclassification
Disaggregation of revenue
Revenue from contracts with customers		(2)
UScellular | Transferred over time | Inbound roaming
Disaggregation of revenue
Revenue from contracts with customers	21	28
UScellular | Transferred over time | Residential
Disaggregation of revenue
Revenue from contracts with customers	0	0
UScellular | Transferred over time | Commercial
Disaggregation of revenue
Revenue from contracts with customers	0	0
UScellular | Transferred over time | Wholesale
Disaggregation of revenue
Revenue from contracts with customers	0	0
UScellular | Transferred over time | Other service
Disaggregation of revenue
Revenue from contracts with customers	42	40
UScellular | Transferred over time | Other service | Prior period reclassification
Disaggregation of revenue
Revenue from contracts with customers		2
UScellular | Transferred at point in time | Equipment and product sales
Disaggregation of revenue
Revenue from contracts with customers	223	252
TDS Telecom
Disaggregation of revenue
Revenue from contracts with customers	251	248
Operating lease income	1	1
Total operating revenues	251	249
TDS Telecom | Transferred over time
Disaggregation of revenue
Revenue from contracts with customers	250	248
TDS Telecom | Transferred over time | Retail service
Disaggregation of revenue
Revenue from contracts with customers	0	0
TDS Telecom | Transferred over time | Inbound roaming
Disaggregation of revenue
Revenue from contracts with customers	0	0
TDS Telecom | Transferred over time | Residential
Disaggregation of revenue
Revenue from contracts with customers	163	157
TDS Telecom | Transferred over time | Commercial
Disaggregation of revenue
Revenue from contracts with customers	44	47
TDS Telecom | Transferred over time | Wholesale
Disaggregation of revenue
Revenue from contracts with customers	44	45
TDS Telecom | Transferred over time | Other service
Disaggregation of revenue
Revenue from contracts with customers	0	0
TDS Telecom | Transferred at point in time | Equipment and product sales
Disaggregation of revenue
Revenue from contracts with customers	0	0
Corporate, Eliminations and Other
Disaggregation of revenue
Revenue from contracts with customers	47	40
Operating lease income	6	5
Total operating revenues	54	46
Corporate, Eliminations and Other | Transferred over time
Disaggregation of revenue
Revenue from contracts with customers	17	16
Corporate, Eliminations and Other | Transferred over time | Retail service
Disaggregation of revenue
Revenue from contracts with customers	0	0
Corporate, Eliminations and Other | Transferred over time | Inbound roaming
Disaggregation of revenue
Revenue from contracts with customers	0	0
Corporate, Eliminations and Other | Transferred over time | Residential
Disaggregation of revenue
Revenue from contracts with customers	0	0
Corporate, Eliminations and Other | Transferred over time | Commercial
Disaggregation of revenue
Revenue from contracts with customers	0	0
Corporate, Eliminations and Other | Transferred over time | Wholesale
Disaggregation of revenue
Revenue from contracts with customers	0	0
Corporate, Eliminations and Other | Transferred over time | Other service
Disaggregation of revenue
Revenue from contracts with customers	17	16
Corporate, Eliminations and Other | Transferred at point in time | Equipment and product sales
Disaggregation of revenue
Revenue from contracts with customers	$ 30	$ 24