v3.26.3
DEBT - Bank borrowings (Details)
€ in Millions, ¥ in Millions, $ in Millions
1 Months Ended 6 Months Ended 12 Months Ended
Aug. 31, 2026
CNY (¥)
Jun. 30, 2026
CNY (¥)
Dec. 31, 2025
CNY (¥)
Nov. 30, 2025
USD ($)
Oct. 31, 2025
USD ($)
Jul. 31, 2025
CNY (¥)
Mar. 31, 2024
EUR (€)
Jun. 30, 2026
CNY (¥)
Jun. 30, 2026
USD ($)
Dec. 31, 2025
CNY (¥)
Dec. 31, 2025
USD ($)
Dec. 31, 2024
CNY (¥)
Jun. 30, 2026
EUR (€)
Jun. 30, 2026
USD ($)
Dec. 31, 2025
EUR (€)
Syndicated loan contract entered in march 2024                              
DEBT                              
Term of debt instrument             5 years                
Maximum borrowing amount | €             € 400                
Debt Instrument, Variable Interest Rate, Type [Extensible Enumeration]               us-gaap:PrimeRateMember us-gaap:PrimeRateMember            
Percentage points added to the reference rate               0.55% 0.55%            
Credit facility drew down amount                       ¥ 340      
Repayment of line of credit facility               ¥ 25   ¥ 40   ¥ 15      
Outstanding loan amount   ¥ 260 ¥ 285         ¥ 260   ¥ 285          
Interest rate (as a percent)   2.45% 2.55%         2.45%   2.55%     2.45% 2.45% 2.55%
Syndicated loan contract entered in march 2024 | Buildings                              
DEBT                              
Amount pledged as collateral for the loan | €                         € 471   € 478
Syndicated loan contract entered in march 2024 | Land use rights                              
DEBT                              
Amount pledged as collateral for the loan | €                         € 66   € 67
Loan facility entered in July 2025                              
DEBT                              
Term of debt instrument           1 year                  
Maximum borrowing amount           ¥ 2,000                  
Credit facility drew down amount           ¥ 1,400                  
Interest rate (as a percent)           1.80%                  
Uncommitted revolving loan facility entered in October 2025                              
DEBT                              
Term of debt instrument         1 year                    
Maximum borrowing amount | $         $ 100                    
Credit facility drew down amount               ¥ 693     $ 0        
Expected extension term         36 months                    
Interest rate (as a percent)   1.90%           1.90%         1.90% 1.90%  
Uncommitted revolving loan facility entered in November 2025                              
DEBT                              
Term of debt instrument       1 year                      
Maximum borrowing amount | $       $ 50                      
Credit facility drew down amount               ¥ 335     0        
Expected extension term       36 months                      
Interest rate (as a percent)   1.90%           1.90%         1.90% 1.90%  
Uncommitted revolving loan facility entered in December 2025                              
DEBT                              
Term of debt instrument     1 year                        
Maximum borrowing amount     ¥ 450             ¥ 450          
Credit facility drew down amount               ¥ 0              
Expected extension term     36 months                        
Uncommitted revolving loan facility entered in December 2025 | Subsequent Event                              
DEBT                              
Credit facility drew down amount ¥ 100                            
Uncommitted revolving loan facility entered in June 2026                              
DEBT                              
Term of debt instrument   1 year                          
Maximum borrowing amount | $                           $ 100  
Credit facility drew down amount               ¥ 660              
Expected extension term   36 months                          
Interest rate (as a percent)   1.90%           1.90%         1.90% 1.90%  
Term loan and revolving credit facility entered in November 2025                              
DEBT                              
Term of debt instrument       12 months                      
Maximum borrowing amount | $       $ 300                      
Credit facility drew down amount | $                 $ 300   $ 0        
Expected extension term       36 months                      
Term loan and revolving credit facility entered in November 2025 | Minimum                              
DEBT                              
Interest rate (as a percent)   1.82%           1.82%         1.82% 1.82%  
Term loan and revolving credit facility entered in November 2025 | Maximum                              
DEBT                              
Interest rate (as a percent)   2.39%           2.39%         2.39% 2.39%