v3.26.1
INVESTMENT SECURITIES - Schedule of trading and available-for-sale securities (Details) - USD ($)
$ in Thousands
Jun. 30, 2026
Mar. 31, 2026
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Total trading securities $ 2,974,677 $ 2,339,100
Total available-for-sale securities, at fair value 686,784 574,038
Allowance (285) (237)
Total held-to-maturity securities 521,521 429,423
Total investment securities 4,182,982 3,342,561
Non-U.S. sovereign debt    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Total trading securities 2,073,085 1,337,577
Total available-for-sale securities, at fair value 242,009 240,453
Held to maturity 486,448 429,660
Total held-to-maturity securities 486,195 429,423
Corporate debt    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Total trading securities 682,474 793,850
Total available-for-sale securities, at fair value 422,690 311,604
Total held-to-maturity securities 35,326  
Corporate equity    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Total trading securities 148,815 166,394
U.S. sovereign debt    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Total trading securities 32,778 33,060
Total available-for-sale securities, at fair value 22,085 21,981
Exchange traded notes and funds    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Total trading securities 37,525 8,219
Corporate debt    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Held to maturity $ 35,358 $ 0