SECURITIES - Amortized Cost and Fair Value of Securities Available for Sale (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 3,760	$ 3,416
Gross Unrealized Gains	1	36
Gross Unrealized Losses	(369)	(26)
Fair Value	3,392	3,426
U.S. Treasury
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	279	205
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(23)	(1)
Fair Value	256	204
U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	116	154
Gross Unrealized Gains	1	1
Gross Unrealized Losses	0	0
Fair Value	117	155
U.S. government-sponsored entities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	284	194
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(23)	(2)
Fair Value	261	192
Agency mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,427	1,342
Gross Unrealized Gains	0	19
Gross Unrealized Losses	(147)	(4)
Fair Value	1,280	1,357
Agency collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,158	1,192
Gross Unrealized Gains	0	11
Gross Unrealized Losses	(136)	(17)
Fair Value	1,022	1,186
Commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	442	294
Gross Unrealized Gains	0	5
Gross Unrealized Losses	(35)	(2)
Fair Value	407	297
States of the U.S. and political subdivisions (municipals)
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	33	33
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(4)	0
Fair Value	29	33
Other debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	21	2
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1)	0
Fair Value	$ 20	$ 2

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27161-111563

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- Definition

Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
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- Definition

Amortized cost excluding accrued interest, before allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

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Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
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