Debt Instrument, Average Amount Outstanding During Period

No definition available.

Name:	tmus_DebtInstrumentAverageAmountOutstandingDuringPeriod
Namespace Prefix:	tmus_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

+ Details

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

- Definition

The average effective interest rate during the reporting period.

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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- 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.

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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

- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amortized cost, before allowance for credit loss, of financing receivable classified as current. Excludes net investment in lease.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The cash inflow from a borrowing with the highest claim on the assets of the entity in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle, if longer).

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with maturities due beyond one year or the operating cycle, if longer.

+ References

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

- Definition

The cash outflow for a long-term debt where the holder has highest claim on the entity's asset in case of bankruptcy or liquidation during the period.

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- Details

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Debt - Narrative (Details) - USD ($)			3 Months Ended
Debt - Narrative (Details) - USD ($)	Apr. 15, 2025	Mar. 17, 2025	Mar. 31, 2025	Mar. 31, 2024	Feb. 27, 2025	Jan. 31, 2025
Debt Instrument [Line Items]
Effective interest rate			4.00%	4.10%
Weighted-average debt outstanding during period			$ 80,800,000,000	$ 77,400,000,000
Principal issuances			7,849,000,000
Net proceeds from issuance of long-term debt			7,768,000,000
ABS Notes
Debt Instrument [Line Items]
Net proceeds from issuance of long-term debt			498,000,000
ABS notes			1,857,000,000
Gross EIP receivables			2,500,000,000
Loans Payable
Debt Instrument [Line Items]
Principal issuances			1,000,000,000
Net proceeds from issuance of long-term debt			970,000,000
Financing commitment, amount						$ 1,000,000,000
Proceeds from loan withdrawal		$ 1,000,000,000
Senior Notes
Debt Instrument [Line Items]
Principal issuances			6,349,000,000
Net proceeds from issuance of long-term debt			$ 6,300,000,000
A Senior Class \| ABS Notes
Debt Instrument [Line Items]
Principal issuances					$ 500,000,000
Interest rate, stated percentage					4.74%
3.500% Senior Notes due 2025 \| Senior Notes \| Subsequent Event
Debt Instrument [Line Items]
Repayments of senior debt	$ 3,000,000,000
Interest rate, stated percentage	3.50%