INVESTMENT SECURITIES - Gains (Losses) Within Investment Income (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Investments, Debt and Equity Securities [Abstract]
Gross gains on investment securities	$ 0	$ 2	$ 15	$ 41
Gross losses on investment securities	(4)	(52)	(65)	(58)
Gross gains on equity securities	0	51	1	51
Gross losses on equity securities	0	0	0	(170)
Net recognized (losses) gains on investment securities	$ (4)	$ 1	$ (49)	$ (136)

Debt Securities, Realized Gain, Gross

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- Definition

Debt Securities, Realized Loss, Gross

+ References

No definition available.

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- Definition

Amount of unrealized and realized gain (loss) on investment in debt and equity securities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(7)(c))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(9)(a))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

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- Definition

Amount of realized gain from sale of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 321
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479536/321-10-50-4

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Amount of realized loss from sale of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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