Intangible Assets (Details) - Licenses $ in Millions	6 Months Ended
Jun. 30, 2019 USD ($)
Licenses
Balance, beginning of period	$ 2,186
Acquisitions	257
Exchanges - Licenses received	26
Balance, end of period	$ 2,469

Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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- Definition

Amount of increase in assets, excluding financial assets and goodwill, lacking physical substance with an indefinite life, from an acquisition.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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Period Type:	duration

- Definition

Amount of assets received, excluding financial assets and goodwill, lacking physical substance with an indefinite life, from an exchange.

+ References

No definition available.

+ Details

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Namespace Prefix:	usm_
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- Details

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