DERIVATIVES - Schedule of Fair Value Hedges (Details) - Hedge of interest rate risk - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Interest expense - long-term borrowed funds
Derivative Instruments, Gain (Loss) [Line Items]
Derivative	$ 10	$ (69)	$ (72)
Hedged Item	(10)	68	71
Interest and fees on other loans held for sale
Derivative Instruments, Gain (Loss) [Line Items]
Derivative	0	13	0
Hedged Item	0	(13)	0
Interest income - investment securities
Derivative Instruments, Gain (Loss) [Line Items]
Derivative	(48)	29	68
Hedged Item	$ 50	$ (29)	$ (68)

Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 815
-SubTopic 25
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480238/815-25-50-1

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- Definition

Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

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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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4E
-Publisher FASB
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