SECURITIES - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Accrued interest receivable on debt securities	$ 139	$ 125
Taxable interest income from investment securities	$ 1,700	1,700	$ 1,200
Held-to-maturity, zero expected credit loss, percent of portfolio	96.00%
Securities sold under agreements to repurchase
Debt Securities, Available-for-sale [Line Items]
Debt securities at fair value	$ 3,400	$ 4,000