v3.26.1
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - USD ($)
$ in Thousands
3 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 01, 2026
Mar. 31, 2026
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Fee and commission income $ 156,734 $ 107,642    
Interest income on margin loans to customers 108,190 60,289    
Goodwill 52,995 48,471   $ 51,099
ChessBase GmbH        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Goodwill     $ 2,073  
Percentage of voting interests acquired     100.00%  
Single non-related party | Revenue benchmark | Customer concentration risk        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Fee and commission income 89,806 72,325    
Interest income on margin loans to customers $ 11,080 $ 8,947