Basis of Presentation - Narrative (Details)	Mar. 31, 2019
TDS \| U.S. Cellular
Basis of Presentation [Line Items]
Ownership percentage	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