SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Fair value measurements - Recurring (Details) - CNY (¥) ¥ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
| Fair value of short term investments | ¥ 5,197 | ¥ 13,586 | ¥ 30,158 |
| Recurring | Level 1 | Fair Value | |||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
| Short-term investments, Fair value | 0 | 0 | |
| Recurring | Level 2 | Fair Value | |||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
| Short-term investments, Fair value | 220,877 | 362,195 | |
| Recurring | Level 3 | Fair Value | |||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
| Short-term investments, Fair value | ¥ 0 | ¥ 0 | |