XML 81 R68.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Leases - Narrative (Details) - USD ($) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Jan. 01, 2019
Leases |  |  |
Cumulative effect of accounting change | $ 2,000,000 | $ 176,000,000 |
Rent expense | 173,000,000 | 166,000,000 |
Retained earnings |  |  |
Leases |  |  |
Cumulative effect of accounting change | $ 2,000,000 | $ 175,000,000 |
Minimum | ASC 842 | Retained earnings |  |  |
Leases |  |  |
Cumulative effect of accounting change |  |  | $ 0

X
- Definition Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption. + References No definition available. + Details
Name: | us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line. + References No definition available. + Details
Name: | us-gaap_LeaseAndRentalExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition [Line Items] for Leases [Table] + References No definition available. + Details
Name: | usm_LeasesLineItems
Namespace Prefix: | usm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_RetainedEarningsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201602Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |