TRADING AND AVAILABLE FOR SALE SECURITIES AT FAIR VALUE - Narrative (Details) $ in Thousands  | 
9 Months Ended | 12 Months Ended | 
|---|---|---|
| 
 Dec. 31, 2021  
USD ($)  
issuer 
 | 
 Mar. 31, 2021  
USD ($)  
issuer 
 | 
|
| Defined Benefit Plan Disclosure [Line Items] | ||
| Number of issuers | issuer | 2 | 2 | 
| Trading securities | $ 1,348,656 | $ 736,188 | 
| Corporate equity | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Trading securities | $ 161,550 | $ 47,340 | 
| Kazakhstan Sustainability Fund JSC | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Percentage of trading securities | 10.00% | 10.00% | 
| Debt securities | $ 297,214 | $ 193,677 | 
| Ministry of Finance of the Republic of Kazakhstan | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Percentage of trading securities | 10.00% | 10.00% | 
| Debt securities | $ 374,982 | $ 293,451 | 
| Public Joint Stock Company, St. Petersburg Exchange | Corporate equity | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Trading securities | $ 140,257 | 
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- Definition Number of Debt Securities Issuers No definition available. 
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- Definition Percentage of Trading Securities No definition available. 
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- Definition Amount of investment in debt security measured at amortized cost (held-to-maturity), investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) and investment in debt security measured at fair value with change in fair value recognized in net income (trading). No definition available. 
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading). Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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