| **SECURITIES FINANCING ACTIVITIES - Gross Amounts of Liabilities Associated with Repurchase Agreements and Securities Lending Agreements by Class of Underlying Collateral (Details) - USD ($) $ in Thousands** | Jun. 30, 2023 | Dec. 31, 2022 |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|---------------|
| **Assets Sold under Agreements to Repurchase [Line Items]**                                                                                                                                                     |          |          |
| Repurchase agreements                                                                                                                                                                                           | $ 47,856,512  | $ 37,333,394  |
| Securities lending                                                                                                                                                                                              | 33,192        |          |
| Total                                                                                                                                                                                                           | 47,889,704    |          |
| U.S. Treasury                                                                                                                                                                                                   |          |          |
| **Assets Sold under Agreements to Repurchase [Line Items]**                                                                                                                                                     |          |          |
| Repurchase agreements                                                                                                                                                                                           | 27,806,994    | 22,477,916    |
| Securities lending                                                                                                                                                                                              | 0             |          |
| Total                                                                                                                                                                                                           | 27,806,994    |          |
| Residential agency MBS                                                                                                                                                                                          |          |          |
| **Assets Sold under Agreements to Repurchase [Line Items]**                                                                                                                                                     |          |          |
| Repurchase agreements                                                                                                                                                                                           | 18,110,937    | 13,223,958    |
| Securities lending                                                                                                                                                                                              | 0             |          |
| Total                                                                                                                                                                                                           | 18,110,937    |          |
| Corporate and other securities                                                                                                                                                                                  |          |          |
| **Assets Sold under Agreements to Repurchase [Line Items]**                                                                                                                                                     |          |          |
| Repurchase agreements                                                                                                                                                                                           | 1,938,581     | $ 1,631,520   |
| Securities lending                                                                                                                                                                                              | 33,192        |          |
| Total                                                                                                                                                                                                           | $ 1,971,773   |          |

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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.
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| - Definition
Amount, before effects of master netting arrangements, of derivative liabilities, securities sold under agreements to repurchase and securities loaned. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.
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| - Definition
Amount, before effects of master netting arrangements, of securities loaned to entities in exchange for collateral. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.
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Amount, before effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.
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