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Defined Contribution Plan, Employer Matching Contribution, Percent of Match up to 50% from Annual Bonus

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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested but were not issued.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement. The equity award is vested but not issued.

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Change in units based on approved performance factors

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Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Change in units based on approved performance factors, Weighted Average Grant Date Fair Value

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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-Name Accounting Standards Codification
-Topic 718
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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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- Definition

Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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- Definition

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

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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Percentage of vesting of award under share-based payment arrangement.

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Number, before forfeiture, of shares issued under share-based payment arrangement. Excludes employee stock ownership plan (ESOP).

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Stock-Based Compensation - UScellular, Nonvested shares and other stock compensation disclosures (Details) - Common Shares - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
UScellular Long-Term Incentive Plans \| Restricted Stock Units
Stock based compensation, Nonvested shares rollforward, number of shares
Nonvested stock units, beginning of period - Number of shares (in shares)	1,461,000
Granted number of shares (in shares)	1,020,000
Vested number of shares (in shares)	(653,000)
Forfeited number of shares (in shares)	(168,000)
Nonvested stock units, end of period - Number of shares (in shares)	1,660,000	1,461,000
Stock based compensation, Nonvested shares weighted average grant date fair value
Nonvested stock units - beginning of period weighted average grant date fair value (USD per share)	$ 40.90
Granted weighted average grant date fair value (USD per share)	29.18	$ 46.81	$ 38.19
Vested weighted average grant date fair value (USD per share)	35.54
Forfeited weighted average grant date fair value (USD per share)	34.81
Nonvested stock units - end of period weighted average grant date fair value (USD per share)	$ 36.43	$ 40.90
Shares issued and granted under stock compensation plans
Fair value of vested stock units	$ 20,000,000	$ 25,000,000	$ 16,000,000
UScellular Long-Term Incentive Plans \| Restricted Stock Units \| UScellular
Shares issued and granted under stock compensation plans
Award vesting period	3 years
UScellular Long-Term Incentive Plans \| Performance Share Units
Stock based compensation, Nonvested shares rollforward, number of shares
Nonvested stock units, beginning of period - Number of shares (in shares)	1,245,000
Granted number of shares (in shares)	582,000
Vested number of shares (in shares)	(398,000)
Change in units based on approved performance factors number of shares	20,000
Forfeited number of shares (in shares)	(144,000)
Nonvested stock units, end of period - Number of shares (in shares)	1,305,000	1,245,000
Stock based compensation, Nonvested shares weighted average grant date fair value
Nonvested stock units - beginning of period weighted average grant date fair value (USD per share)	$ 40.16
Granted weighted average grant date fair value (USD per share)	29.71	$ 46.43	$ 38.81
Vested weighted average grant date fair value (USD per share)	36.92
Change in units based on approved performance factors weighted average grant date fair value (USD per share)	46.43
Forfeited weighted average grant date fair value (USD per share)	40.05
Nonvested stock units - end of period weighted average grant date fair value (USD per share)	$ 36.60	$ 40.16
Shares issued and granted under stock compensation plans
Fair value of vested stock units	$ 11,000,000		$ 0
UScellular Long-Term Incentive Plans \| Performance Share Units \| UScellular
Shares issued and granted under stock compensation plans
Award vesting period	3 years
UScellular Long-Term Incentive Plans \| Performance Share Units \| Minimum
Shares issued and granted under stock compensation plans
Performance share awards target	50.00%
UScellular Long-Term Incentive Plans \| Performance Share Units \| Maximum
Shares issued and granted under stock compensation plans
Fair value of vested stock units		$ 1,000,000
Performance share awards target	200.00%
UScellular Long-Term Incentive Plans \| Deferred Compensation Stock Units
Stock based compensation, Nonvested shares weighted average grant date fair value
Granted weighted average grant date fair value (USD per share)	$ 31.79	$ 0	$ 40.72
Shares issued and granted under stock compensation plans
Fair value of vested stock units	$ 1,000,000
Percent of match up to 50% from annual bonus	25.00%
Percent of match above 50% from annual bonus	33.00%
Award vesting period	3 years
Vested number of shares, unissued	63,000
Vested number of shares, unissued, fair value	$ 2,000,000
UScellular Long-Term Incentive Plans \| Deferred Compensation Stock Units \| Maximum
Shares issued and granted under stock compensation plans
Fair value of vested stock units		$ 1,000,000	$ 1,000,000
Non-Employee Directors' Plan \| UScellular
Shares issued and granted under stock compensation plans
Shares issued	19,000	13,000	18,000