Receivables and Related Allowance for Credit Losses - Schedule of Write Offs Net of Recoveries (Details) $ in Millions	12 Months Ended
Dec. 31, 2023 USD ($)
Receivables [Abstract]
Originated in 2023	$ 174
Originated in 2022	284
Originated prior to 2022	60
Total Write-offs	$ 518

Financing Receivable, Year Three, Write Offs, Two Years before Current Fiscal Year

No definition available.

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