| NET INTEREST INCOME/EXPENSE | NET INTEREST INCOME/EXPENSE Net interest income/expense for the three months ended December 31, 2024, and December 31, 2023 included the following: 
 
|  |  |  |  |  |  |  |  |  |  |  |  |  
|  | Three months ended December 31, 2024 |  | Three months ended December 31, 2023 |  
| Interest income: |  |  |  |  
| Interest income on trading securities | 95,666 |  |  | $ | 112,860 |  |  
| Interest income on margin loans to customers | 61,295 |  |  | 51,553 |  |  
| Interest income on loans to customers | 51,089 |  |  | 49,529 |  |  
| Interest income on securities available-for-sale | 11,027 |  |  | 7,478 |  |  
| Interest income on reverse repurchase agreements and amounts due from banks | 5,611 |  |  | 5,025 |  |  
| Total interest income | $ | 224,688 |  |  | $ | 226,445 |  |  
|  |  |  |  |  
| Interest expense: |  |  |  |  
| Interest expense on securities repurchase agreement obligations | $ | 88,526 |  |  | $ | 110,778 |  |  
| Interest expense on customer accounts and deposits | 27,288 |  |  | 15,653 |  |  
| Interest expense on debt securities issued | 9,974 |  |  | 1,491 |  |  
| Interest expense on margin lending payable | 4,818 |  |  | 3,211 |  |  
| Interest expense on loans received | 530 |  |  | 36 |  |  
| Other interest expense | — |  |  | 54 |  |  
| Total interest expense | $ | 131,136 |  |  | $ | 131,223 |  |  
|  |  |  |  |  
| Net interest income | $ | 93,552 |  |  | $ | 95,222 |  | 
 Net interest income/expense for the nine months ended December 31, 2024, and December 31, 2023 includes: 
|  |  |  |  |  |  |  |  |  |  |  |  |  
|  | Nine months ended December 31, 2024 |  | Nine months ended December 31, 2023 |  
| Interest income: |  |  |  |  
| Interest income on trading securities | $ | 307,786 |  |  | $ | 313,739 |  |  
| Interest income on margin loans to customers | 153,279 |  |  | 111,306 |  |  
| Interest income on loans to customers | 152,849 |  |  | 123,730 |  |  
| Interest income on securities available-for-sale | 28,430 |  |  | 25,476 |  |  
| Interest income on reverse repurchase agreements and amounts due from banks | 18,672 |  |  | 12,012 |  |  
| Other interest income | — |  |  | 2,594 |  |  
| Total interest income | $ | 661,016 |  |  | $ | 588,857 |  |  
|  |  |  |  |  
| Interest expense: |  |  |  |  
| Interest expense on securities repurchase agreement obligations | $ | 267,049 |  |  | $ | 303,242 |  |  
| Interest expense on customer accounts and deposits | 74,111 |  |  | 49,120 |  |  
| Interest expense on margin lending payable | 35,357 |  |  | 9,671 |  |  
| Interest expense on debt securities issued | 23,912 |  |  | 3,387 |  |  
| Interest expense on loans received | 1,042 |  |  | 89 |  |  
| Other interest expense | 48 |  |  | 141 |  |  
| Total interest expense | $ | 401,519 |  |  | $ | 365,650 |  |  
|  |  |  |  |  
| Net interest income | $ | 259,497 |  |  | $ | 223,207 |  |  |