| Document and Entity Information | Apr. 06, 2021 |
| Cover [Abstract] | |
| Entity Incorporation State Country Code | DE |
| Amendment Flag | false |
| Entity Central Index Key | 0001283699 |
| Document Type | 8-K |
| Document Period End Date | Apr. 6, 2021 |
| Entity Registrant Name | T-MOBILE US, INC. |
| Entity File Number | 1-33409 |
| Entity Tax Identification Number | 20-0836269 |
| Entity Address, Address Line One | 12920 SE 38th Street |
| Entity Address, City or Town | Bellevue |
| Entity Address, State or Province | WA |
| Entity Address, Postal Zip Code | 98006-1350 |
| City Area Code | (425) |
| Local Phone Number | 378-4000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $0.00001 par value per share |
| Trading Symbol | TMUS |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
