| Cover | Jan. 07, 2020 |
| Cover page. | |
| Document Type | 8-K |
| Document Period End Date | Jan. 7, 2020 |
| Entity Registrant Name | T-MOBILE US, INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 1-33409 |
| Entity Tax Identification Number | 20-0836269 |
| Entity Central Index Key | 0001283699 |
| Amendment Flag | false |
| 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 |
| Title of 12(b) Security | Common Stock, par value $0.00001 per share |
| Trading Symbol | TMUS |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
