Principal Accounting Policies - Property and equipment, net (Details) |
Dec. 31, 2025 |
|---|---|
| Computers | |
| Property and Equipment | |
| Property, Plant and Equipment, Useful Life | 3 years |
| Equipment, furniture and motor vehicles | |
| Property and Equipment | |
| Property, Plant and Equipment, Useful Life | 5 years |
| Leasehold improvements | |
| Property and Equipment | |
| Property, Plant, and Equipment, Useful Life, Term, Description [Extensible Enumeration] | us-gaap:UsefulLifeShorterOfTermOfLeaseOrAssetUtilityMember |