Summary of significant accounting policies - Property and equipment, net, Intangible assets and Impairment long-lived assets (Details) |
Dec. 31, 2025 |
|---|---|
| Summary of significant accounting policies | |
| Leasehold Improvements | us-gaap:UsefulLifeShorterOfTermOfLeaseOrAssetUtilityMember |
| Minimum | |
| Summary of significant accounting policies | |
| Intangible assets useful life | 1 year |
| Maximum | |
| Summary of significant accounting policies | |
| Intangible assets useful life | 10 years |
| Computer and transmission equipment | |
| Summary of significant accounting policies | |
| Property and equipment useful life | 3 years |
| Furniture and office equipment | |
| Summary of significant accounting policies | |
| Property and equipment useful life | 5 years |
| Motor vehicles | |
| Summary of significant accounting policies | |
| Property and equipment useful life | 4 years |