Basis of Presentation - Narrative (Details)	Sep. 30, 2020
UScellular
Basis of Presentation [Line Items]
TDS ownership of UScellular	82.00%

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

No definition available.

Name:	us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant