INVESTMENT SECURITIES - Narrative (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2024 USD ($) security shares	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Jan. 24, 2024 USD ($) shares
Schedule of Investments [Line Items]
Debt securities, available-for-sale, accrued Interest	$ 177,000,000	$ 87,000,000
Debt Securities, held-to-maturity, accrued interest	20,000,000	18,000,000
Write off of accrued interest receivable	$ 0	0
Debt securities, held-to-maturity, threshold period past due	30 days
Securities past due	$ 10,239,000,000	9,979,000,000
Realized gains on marketable equity securities sold	$ 6,000,000	0	$ 0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, number of positions | security	486
Investment securities available for sale, allowance for credit loss	$ 0
Securities, nonaccrual	0	0
Total Past Due
Schedule of Investments [Line Items]
Securities past due	0	0
Asset Pledged as Collateral
Schedule of Investments [Line Items]
Investment securities, aggregate carrying value, pledged as collateral	$ 3,940,000,000	$ 3,770,000,000
Visa, Inc | Class B
Schedule of Investments [Line Items]
Investment owned (in shares) | shares	354
Investment owned, carrying value	$ 0
Visa, Inc | Class B-1
Schedule of Investments [Line Items]
Investment owned (in shares) | shares				354
Investment owned, carrying value				$ 0
Government sponsored enterprise-issued mortgage-backed securities, government agency securities, or U.S. treasury securities
Schedule of Investments [Line Items]
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, number of positions | security	420
Corporate bonds
Schedule of Investments [Line Items]
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, number of positions | security	66