INVESTMENT SECURITIES - Schedule of Gross Unrealized Losses and Fair Value by Investment Category (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Fair Value
Less than 12 months	$ 7,198	$ 3,621
12 months or more	9,104	11,046
Total	16,302	14,667
Gross Unrealized Losses
Less than 12 months	(178)	(28)
12 months or more	(1,231)	(1,300)
Total	(1,409)	(1,328)
U.S. Treasury and agency obligations
Fair Value
Less than 12 months	2,343	1,899
12 months or more	456	431
Total	2,799	2,330
Gross Unrealized Losses
Less than 12 months	(68)	(12)
12 months or more	(42)	(39)
Total	(110)	(51)
Mortgage-backed securities
Fair Value
Less than 12 months	1,766	958
12 months or more	2,203	2,269
Total	3,969	3,227
Gross Unrealized Losses
Less than 12 months	(50)	(12)
12 months or more	(459)	(413)
Total	(509)	(425)
Tax-exempt municipal securities
Fair Value
Less than 12 months	97	160
12 months or more	405	523
Total	502	683
Gross Unrealized Losses
Less than 12 months	(1)	(1)
12 months or more	(21)	(21)
Total	(22)	(22)
Residential
Fair Value
Less than 12 months	130	0
12 months or more	343	373
Total	473	373
Gross Unrealized Losses
Less than 12 months	(2)	0
12 months or more	(62)	(66)
Total	(64)	(66)
Commercial
Fair Value
Less than 12 months	58	18
12 months or more	992	1,303
Total	1,050	1,321
Gross Unrealized Losses
Less than 12 months	(1)	0
12 months or more	(84)	(126)
Total	(85)	(126)
Asset-backed securities
Fair Value
Less than 12 months	419	120
12 months or more	436	1,364
Total	855	1,484
Gross Unrealized Losses
Less than 12 months	(5)	(1)
12 months or more	(19)	(43)
Total	(24)	(44)
Corporate debt securities
Fair Value
Less than 12 months	2,385	466
12 months or more	4,269	4,783
Total	6,654	5,249
Gross Unrealized Losses
Less than 12 months	(51)	(2)
12 months or more	(544)	(592)
Total	$ (595)	$ (594)