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INVESTMENT SECURITIES - Schedule of Amortized Cost and Fair Value of Securities Available for Sale (Details) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 3,666	$ 3,620
Gross Unrealized Gains	23	4
Gross Unrealized Losses	(109)	(158)
Fair  Value	3,580	3,466
U.S. Treasury
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	274	274
Gross Unrealized Gains	1	1
Gross Unrealized Losses	0	(1)
Fair  Value	275	274
U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	45	53
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair  Value	45	53
U.S. GSE
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	304	302
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1)	(2)
Fair  Value	303	300
Agency MBS
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	780	714
Gross Unrealized Gains	5	0
Gross Unrealized Losses	(11)	(20)
Fair  Value	774	694
Agency CMO
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	727	796
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(75)	(98)
Fair  Value	652	698
Agency commercial MBS
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,475	1,420
Gross Unrealized Gains	16	3
Gross Unrealized Losses	(20)	(35)
Fair  Value	1,471	1,388
States of the U.S. and political subdivisions (municipals)
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	21	24
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(2)	(2)
Fair  Value	19	22
Other debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	40	37
Gross Unrealized Gains	1	0
Gross Unrealized Losses	0	0
Fair  Value	$ 41	$ 37

X

- Definition

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).

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