v3.26.1
Summary of significant accounting policies - Certain risks and concentrations (Details) - Institution
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Accounts Receivable    
Concentration Risk [Line Items]    
Number of institutional cooperators 2 3
Loan facilitated 10.00% 10.00%
Accounts Receivable | Customer Concentration Risk | Institutional Cooperator A    
Concentration Risk [Line Items]    
Concentration, risk percentage   12.20%
Accounts Receivable | Customer Concentration Risk | Institutional Cooperator B    
Concentration Risk [Line Items]    
Concentration, risk percentage   14.10%
Accounts Receivable | Customer Concentration Risk | Institutional Cooperator C    
Concentration Risk [Line Items]    
Concentration, risk percentage 10.20% 10.80%
Accounts Receivable | Customer Concentration Risk | Institutional Cooperator D    
Concentration Risk [Line Items]    
Concentration, risk percentage 11.50%  
Total loans    
Concentration Risk [Line Items]    
Number of institutional cooperators 1 2
Loan facilitated 10.00% 10.00%
Total loans | Customer Concentration Risk | Institutional Cooperator A    
Concentration Risk [Line Items]    
Concentration, risk percentage 11.40% 25.20%
Total loans | Customer Concentration Risk | Institutional Cooperator B    
Concentration Risk [Line Items]    
Concentration, risk percentage   10.20%
Deposits    
Concentration Risk [Line Items]    
Number of institutional cooperators 3 1
Loan facilitated 0.10% 0.10%
Deposits | Customer Concentration Risk | Institutional Cooperator B    
Concentration Risk [Line Items]    
Concentration, risk percentage   15.10%
Deposits | Customer Concentration Risk | Institutional Cooperator C    
Concentration Risk [Line Items]    
Concentration, risk percentage 13.20%  
Deposits | Customer Concentration Risk | Institutional Cooperator D    
Concentration Risk [Line Items]    
Concentration, risk percentage 13.20%  
Deposits | Customer Concentration Risk | Institutional Cooperator E    
Concentration Risk [Line Items]    
Concentration, risk percentage 13.50%