SECURITIES - Narrative (Details) - USD ($)	3 Months Ended	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Schedule of Available-for-sale and Held-to-maturity Securities [Line Items]
Accrued interest receivable on debt securities	$ 127,000,000		$ 127,000,000		$ 107,000,000
Taxable interest income from securities	290,000,000	$ 243,000,000	823,000,000	$ 582,000,000
Offsetting of short-term receivables or payables recognized	$ 0		$ 0		$ 0
Held-to-maturity, zero expected credit loss, percent of portfolio	95.00%		95.00%
Allowance for credit loss recognized	$ 0		$ 0
Mortgage-backed securities
Schedule of Available-for-sale and Held-to-maturity Securities [Line Items]
Securitizations of mortgage loans	$ 65,000,000	$ 59,000,000	$ 65,000,000	$ 99,000,000

Debt Securities, Held To Maturity, Zero Expected Credit Loss, Percent Of Portfolio

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- Definition

Debt Securities, Interest Receivable

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- Definition

[Line Items] for Schedule of Available-for-sale and Held-to-maturity Securities [Table]

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- Definition

Amount, excluding accrued interest, of allowance for credit loss on investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479344/326-20-45-1

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- Definition

Amount of operating interest income, including amortization and accretion of premiums and discounts, on securities subject to state, federal and other income tax.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1402
-Paragraph (a)
-Publisher SEC

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1402
-Paragraph (b)
-Subparagraph (1)
-Publisher SEC

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

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- Definition

The cash inflow from securitizing loans held with the intention to resell in the near future.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 16
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-16

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-21

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Amount, before effects of master netting arrangements, of securities loaned to entities in exchange for collateral and funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-SubTopic 20
-Topic 210
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483466/210-20-50-3

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 860
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481420/860-30-50-7

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