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Certain Relationships and Related Transactions (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | May 04, 1988
Related Party Transaction [Line Items] |  |  |  |
Billings to U.S. Cellular from TDS | $ 82 | $ 86 | $ 85 |
TDS | U.S. Cellular |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
TDS ownership percentage | 82.00% |  |  |
TDS | U.S. Cellular | Minimum |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
TDS ownership percentage |  |  |  | 90.00%
Sidley Austin LLP |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
Legal expense | $ 7 | 5 | 7 |
TDS |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
Billings to U.S. Cellular from TDS | $ 82 | $ 86 | $ 85 |

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- Definition The amount of expense provided in the period for legal costs incurred on or before the balance sheet date pertaining to resolved, pending or threatened litigation, including arbitration and mediation proceedings. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.3) -URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227 + Details
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Balance Type: | debit
Period Type: | duration

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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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Data Type: | num:percentItemType
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- Definition Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Details
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Namespace Prefix: |
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Balance Type: |
Period Type: |

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- Details
Name: | srt_OwnershipAxis=usm_UnitedStatesCellularCorporationMember
Namespace Prefix: |
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Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
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Balance Type: |
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- Details
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Balance Type: |
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- Details
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