SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Convenience translation, Employee defined contribution plan (Details) ¥ in Thousands	12 Months Ended
Dec. 31, 2025 CNY (¥) $ / ¥	Dec. 31, 2024 CNY (¥)	Dec. 31, 2023 CNY (¥)
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Convenience translation rate (USD to RMB) \| $ / ¥	6.9931
Defined contribution plan cost \| ¥	¥ 263,396	¥ 238,577	¥ 198,459

Foreign exchange rate used to translate amounts denominated in functional currency to reporting currency.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 830
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481674/830-30-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 830
-SubTopic 30
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479424/830-30-S99-1

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