Income taxes - Withholding tax on undistributed dividends (Details) - CNY (¥) ¥ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Income Tax Disclosure [Abstract] | |||
| Withholding tax rate (in percent) | 10.00% | ||
| Deferred tax liability accrued for dividend withholding taxes | ¥ 0 | ¥ 0 | ¥ 0 |