Revenue Recognition - Disaggregation Of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of revenue
Revenue from contracts with customers	$ 1,235	$ 1,235
Operating lease income	26	22
Total operating revenues	1,261	1,257
Transferred over time
Disaggregation of revenue
Revenue from contracts with customers	1,000	973
Transferred over time | Retail service
Disaggregation of revenue
Revenue from contracts with customers	671	659
Transferred over time | Inbound roaming
Disaggregation of revenue
Revenue from contracts with customers	37	34
Transferred over time | Residential
Disaggregation of revenue
Revenue from contracts with customers	144	131
Transferred over time | Commercial
Disaggregation of revenue
Revenue from contracts with customers	50	54
Transferred over time | Wholesale
Disaggregation of revenue
Revenue from contracts with customers	45	45
Transferred over time | Other service
Disaggregation of revenue
Revenue from contracts with customers	53	50
Transferred at point in time | Equipment and product sales
Disaggregation of revenue
Revenue from contracts with customers	235	262
U.S. Cellular
Disaggregation of revenue
Revenue from contracts with customers	944	950
Operating lease income	19	16
Total operating revenues	963	966
U.S. Cellular | Transferred over time
Disaggregation of revenue
Revenue from contracts with customers	743	725
U.S. Cellular | Transferred over time | Retail service
Disaggregation of revenue
Revenue from contracts with customers	671	659
U.S. Cellular | Transferred over time | Inbound roaming
Disaggregation of revenue
Revenue from contracts with customers	37	34
U.S. Cellular | Transferred over time | Residential
Disaggregation of revenue
Revenue from contracts with customers	0	0
U.S. Cellular | Transferred over time | Commercial
Disaggregation of revenue
Revenue from contracts with customers	0	0
U.S. Cellular | Transferred over time | Wholesale
Disaggregation of revenue
Revenue from contracts with customers	0	0
U.S. Cellular | Transferred over time | Other service
Disaggregation of revenue
Revenue from contracts with customers	35	32
U.S. Cellular | Transferred at point in time | Equipment and product sales
Disaggregation of revenue
Revenue from contracts with customers	201	225
TDS Telecom Total
Disaggregation of revenue
Revenue from contracts with customers	240	230
Operating lease income	1	0
Total operating revenues	240	230
TDS Telecom Total | Transferred over time
Disaggregation of revenue
Revenue from contracts with customers	239	229
TDS Telecom Total | Transferred over time | Retail service
Disaggregation of revenue
Revenue from contracts with customers	0	0
TDS Telecom Total | Transferred over time | Inbound roaming
Disaggregation of revenue
Revenue from contracts with customers	0	0
TDS Telecom Total | Transferred over time | Residential
Disaggregation of revenue
Revenue from contracts with customers	144	131
TDS Telecom Total | Transferred over time | Commercial
Disaggregation of revenue
Revenue from contracts with customers	50	54
TDS Telecom Total | Transferred over time | Wholesale
Disaggregation of revenue
Revenue from contracts with customers	45	45
TDS Telecom Total | Transferred over time | Other service
Disaggregation of revenue
Revenue from contracts with customers	0	0
TDS Telecom Total | Transferred at point in time | Equipment and product sales
Disaggregation of revenue
Revenue from contracts with customers	0	0
TDS Telecom Wireline
Disaggregation of revenue
Revenue from contracts with customers	169	170
Operating lease income	0	0
Total operating revenues	169	171
TDS Telecom Wireline | Transferred over time
Disaggregation of revenue
Revenue from contracts with customers	169	170
TDS Telecom Wireline | Transferred over time | Retail service
Disaggregation of revenue
Revenue from contracts with customers	0	0
TDS Telecom Wireline | Transferred over time | Inbound roaming
Disaggregation of revenue
Revenue from contracts with customers	0	0
TDS Telecom Wireline | Transferred over time | Residential
Disaggregation of revenue
Revenue from contracts with customers	84	81
TDS Telecom Wireline | Transferred over time | Commercial
Disaggregation of revenue
Revenue from contracts with customers	39	43
TDS Telecom Wireline | Transferred over time | Wholesale
Disaggregation of revenue
Revenue from contracts with customers	45	45
TDS Telecom Wireline | Transferred over time | Other service
Disaggregation of revenue
Revenue from contracts with customers	0	0
TDS Telecom Wireline | Transferred at point in time | Equipment and product sales
Disaggregation of revenue
Revenue from contracts with customers	0	0
TDS Telecom Cable
Disaggregation of revenue
Revenue from contracts with customers	71	60
Operating lease income	0	0
Total operating revenues	71	60
TDS Telecom Cable | Transferred over time
Disaggregation of revenue
Revenue from contracts with customers	71	60
TDS Telecom Cable | Transferred over time | Retail service
Disaggregation of revenue
Revenue from contracts with customers	0	0
TDS Telecom Cable | Transferred over time | Inbound roaming
Disaggregation of revenue
Revenue from contracts with customers	0	0
TDS Telecom Cable | Transferred over time | Residential
Disaggregation of revenue
Revenue from contracts with customers	60	49
TDS Telecom Cable | Transferred over time | Commercial
Disaggregation of revenue
Revenue from contracts with customers	11	10
TDS Telecom Cable | Transferred over time | Wholesale
Disaggregation of revenue
Revenue from contracts with customers	0	0
TDS Telecom Cable | Transferred over time | Other service
Disaggregation of revenue
Revenue from contracts with customers	0	0
TDS Telecom Cable | 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	52	55
Operating lease income	6	6
Total operating revenues	58	61
Corporate, Eliminations and Other | Transferred over time
Disaggregation of revenue
Revenue from contracts with customers	18	18
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	18	18
Corporate, Eliminations and Other | Transferred at point in time | Equipment and product sales
Disaggregation of revenue
Revenue from contracts with customers	$ 34	$ 37