SECURITIES BORROWING AND LENDING - Narrative (Details) - USD ($)	Sep. 30, 2025	Dec. 31, 2024
Offsetting Assets [Line Items]
Fair value of securities borrowed from users and third parties	$ 6,465,000,000	$ 3,118,000,000
Fair value of securities pledged to counterparties	14,956,000,000	6,887,000,000
Amount re-pledged with clearing organizations to meet deposit requirements	2,850,000,000	1,600,000,000
Third Parties
Offsetting Assets [Line Items]
Fair value of securities borrowed from users and third parties	0	0
Asset Pledged as Collateral
Offsetting Assets [Line Items]
Securities pledged	19,740,000,000	11,040,000,000.00
Asset Pledged as Collateral | Securities Sold under Agreements to Repurchase
Offsetting Assets [Line Items]
Securities pledged	68,760,000,000	38,700,000,000
Fair value of securities borrowed from users and third parties	$ 6,470,000,000	$ 3,120,000,000