Annual report pursuant to Section 13 and 15(d)

NET GAIN ON TRADING SECURITIES (Details)

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NET GAIN ON TRADING SECURITIES (Details)
 12 Months Ended
Mar. 31, 2022
USD ($)
investor
shares
Mar. 31, 2021
USD ($)
Mar. 31, 2020
USD ($)
Debt Securities, Available-for-sale [Line Items]      
Net gain recognized during the period on trading securities sold during the period $ 206,238,000 $ 19,478,000 $ 18,884,000
Net unrealized (loss)/gain recognized during the reporting period on trading securities still held at the reporting date (49,893,000) 6,433,000 (10,552,000)
Net gain recognized during the period on trading securities 156,345,000 25,911,000 $ 8,332,000
Equity securities FVNI portfolio shares SPBX $ 40,441,000 $ 18,408,000  
Number of equity securities exchanged (in shares) | shares 12,500,000,000    
Number of investors | investor 15,490,000    
Proceeds from the sale of equity securities FVNI $ 167,011,000    
Gain on sale of equity securities 165,693    
Realized gain on sale of equity securities 215,586    
Equity securities, FV-NI, unrealized loss 49,893,000    
Exchange Traded      
Debt Securities, Available-for-sale [Line Items]      
Gain on sale of equity securities 179,216,000    
Realized gain on sale of equity securities 177,146,000    
Equity securities, FV-NI, unrealized loss $ 54,238,000