The number of unites (items of property) subject to the failed sale leaseback arrangement.

No definition available.

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Namespace Prefix:	tmus_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Property Subject to Sale, Number of Units

+ References

No definition available.

+ Details

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Namespace Prefix:	tmus_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Definition

Sale Leaseback Transaction, Fixed-Price Purchase Options

+ References

No definition available.

+ Details

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Namespace Prefix:	tmus_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918673-209980

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

The liability due as of the balance sheet date for leasebacks accounted for using the deposit method.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=84164451&loc=d3e36991-112694

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=77913982&loc=d3e50796-112755

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The financing cost related to leases that have been recorded under the deposit method, as a financing or as a capital leases in connection with the transaction involving the sale of property to another party and the lease of the property back to the seller.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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

Name:	us-gaap_SaleLeasebackTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The net book value of the asset(s) sold in connection with the sale of the property to another party and lease back to the seller.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 40
-Section 55
-Paragraph 51
-URI http://asc.fasb.org/extlink&oid=82846721&loc=d3e51840-112757

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-Name Accounting Standards Codification
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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of cash inflow after closing and debt issuance costs received by a seller-lessee in a sale-leaseback recognized in financing activities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_SaleLeasebackTransactionDescriptionAxis=tmus_TowerTransactionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Balance Type:
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- Details

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Balance Type:
Period Type:

- Details

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Period Type:

Tower Obligations - Narrative (Details) $ in Millions	1 Months Ended	12 Months Ended
Tower Obligations - Narrative (Details) $ in Millions	Nov. 30, 2012	Dec. 31, 2018 USD ($) tower_site	Dec. 31, 2015 USD ($) tower_site	Dec. 31, 2012 USD ($) tower_site	Dec. 31, 2017 USD ($)
Sale Leaseback Transaction [Line Items]
Tower obligations		$ 2,557			$ 2,590
Property and equipment, net		$ 329			$ 402
Tower Transaction
Sale Leaseback Transaction [Line Items]
Property subject to sale, number of units				7,100
Net proceeds, financing activities				$ 2,500
Property subject to failed sale leaseback transaction, number of units \| tower_site				6,200
Lessee leasing arrangements, operating leases, term of contract		10 years		10 years
Sale leaseback transaction, fixed-price purchase options				$ 2,000
Imputed interest rate, financial obligation	8.00%
Tower Transaction \| Minimum
Sale Leaseback Transaction [Line Items]
Lessee leasing arrangements, operating leases, term of contract				23 years
Tower Transaction \| Maximum
Sale Leaseback Transaction [Line Items]
Lessee leasing arrangements, operating leases, term of contract				37 years
Tower Transaction PTI
Sale Leaseback Transaction [Line Items]
Property subject to sale, number of units \| tower_site			600
Net proceeds, financing activities			$ 140
Property subject to failed sale leaseback transaction, number of units \| tower_site		150
Imputed interest rate, financial obligation			5.00%