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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

X

- 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

X

- 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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Balance Type:	na
Period Type:	instant

X

- 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

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X

- 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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X

- Details

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Namespace Prefix:
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X

- Details

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Period Type:

X

- Details

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X

- Details

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- Details

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