Revenue Recognition Disaggregation Of Revenue (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Revenue from contracts with customers
Revenue from contracts with customers	$ 1,203	[1]
Transferred over time
Revenue from contracts with customers
Revenue from contracts with customers	956
Transferred over time | Retail service
Revenue from contracts with customers
Revenue from contracts with customers	649
Transferred over time | Inbound roaming
Revenue from contracts with customers
Revenue from contracts with customers	27
Transferred over time | Residential
Revenue from contracts with customers
Revenue from contracts with customers	126
Transferred over time | Commercial
Revenue from contracts with customers
Revenue from contracts with customers	57
Transferred over time | Wholesale
Revenue from contracts with customers
Revenue from contracts with customers	47
Transferred over time | Other service
Revenue from contracts with customers
Revenue from contracts with customers	50
Transferred at point in time | Equipment and product sales
Revenue from contracts with customers
Revenue from contracts with customers	247
U.S. Cellular
Revenue from contracts with customers
Revenue from contracts with customers	926	[1]
U.S. Cellular | Transferred over time
Revenue from contracts with customers
Revenue from contracts with customers	708
U.S. Cellular | Transferred over time | Retail service
Revenue from contracts with customers
Revenue from contracts with customers	649
U.S. Cellular | Transferred over time | Inbound roaming
Revenue from contracts with customers
Revenue from contracts with customers	27
U.S. Cellular | Transferred over time | Other service
Revenue from contracts with customers
Revenue from contracts with customers	32
U.S. Cellular | Transferred at point in time | Equipment and product sales
Revenue from contracts with customers
Revenue from contracts with customers	218
TDS Telecom
Revenue from contracts with customers
Revenue from contracts with customers	230	[1]
TDS Telecom | Transferred over time
Revenue from contracts with customers
Revenue from contracts with customers	230
TDS Telecom | Transferred over time | Residential
Revenue from contracts with customers
Revenue from contracts with customers	126
TDS Telecom | Transferred over time | Commercial
Revenue from contracts with customers
Revenue from contracts with customers	57
TDS Telecom | Transferred over time | Wholesale
Revenue from contracts with customers
Revenue from contracts with customers	47
TDS Telecom Wireline
Revenue from contracts with customers
Revenue from contracts with customers	175	[1]
TDS Telecom Wireline | Transferred over time
Revenue from contracts with customers
Revenue from contracts with customers	175
TDS Telecom Wireline | Transferred over time | Residential
Revenue from contracts with customers
Revenue from contracts with customers	80
TDS Telecom Wireline | Transferred over time | Commercial
Revenue from contracts with customers
Revenue from contracts with customers	48
TDS Telecom Wireline | Transferred over time | Wholesale
Revenue from contracts with customers
Revenue from contracts with customers	47
TDS Telecom Cable
Revenue from contracts with customers
Revenue from contracts with customers	55	[1]
TDS Telecom Cable | Transferred over time
Revenue from contracts with customers
Revenue from contracts with customers	55
TDS Telecom Cable | Transferred over time | Residential
Revenue from contracts with customers
Revenue from contracts with customers	46
TDS Telecom Cable | Transferred over time | Commercial
Revenue from contracts with customers
Revenue from contracts with customers	10
Corporate, Eliminations and Other
Revenue from contracts with customers
Revenue from contracts with customers	47	[1]
Corporate, Eliminations and Other | Transferred over time
Revenue from contracts with customers
Revenue from contracts with customers	18
Corporate, Eliminations and Other | Transferred over time | Other service
Revenue from contracts with customers
Revenue from contracts with customers	18
Corporate, Eliminations and Other | Transferred at point in time | Equipment and product sales
Revenue from contracts with customers
Revenue from contracts with customers	$ 29

[1] These amounts do not include revenues outside the scope of ASU 2014-09; therefore, revenue line items in this table will not agree to amounts presented in the Consolidated Statement of Operations.