Receivables and Related Allowance for Credit Losses - Schedule of Write Offs Net of Recoveries (Details) $ in Millions	3 Months Ended
Mar. 31, 2024 USD ($)
Write-offs
Originated in 2024	$ 2
Originated in 2023	114
Originated prior to 2023	34
Total Write-offs	$ 150

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

No definition available.

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