SECURITIZATIONS AND VARIABLE INTEREST ENTITIES - Funding Commitments (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	$ 17,871	$ 17,266
Liquidity facilities
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	1,736	1,498
Liquidity facilities | Non-agency-sponsored mortgage securitizations
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	0	0
Liquidity facilities | Asset-based financing
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	0	0
Liquidity facilities | Municipal securities tender option bond trusts (TOBs)
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	1,736	1,498
Liquidity facilities | Municipal investments
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	0	0
Liquidity facilities | Investment funds
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	0	0
Liquidity facilities | Other
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	0	0
Loan / equity commitments
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	16,135	15,768
Loan / equity commitments | Non-agency-sponsored mortgage securitizations
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	11	5
Loan / equity commitments | Asset-based financing
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	12,288	12,189
Loan / equity commitments | Municipal securities tender option bond trusts (TOBs)
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	0	0
Loan / equity commitments | Municipal investments
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	3,821	3,562
Loan / equity commitments | Investment funds
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	15	12
Loan / equity commitments | Other
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	$ 0	$ 0