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Basis of Presentation - Narrative (Details)	Mar. 31, 2021
TDS | UScellular
Basis of Presentation [Line Items]
Ownership percentage	82.00%

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

Used to group disclosures related to significant accounting policies.

+ References

No definition available.

+ Details

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X

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_OwnershipAxis=usm_UnitedStatesCellularCorporationMember
Namespace Prefix:
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Balance Type:
Period Type: