INVESTMENT SECURITIES - Schedule of Gross Unrealized Losses and Fair Value by Investment Category (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Fair Value
Less than 12 months	$ 2,331	$ 7,198
12 months or more	8,740	9,104
Total	11,071	16,302
Gross Unrealized Losses
Less than 12 months	(16)	(178)
12 months or more	(851)	(1,231)
Total	(867)	(1,409)
U.S. Treasury and agency obligations
Fair Value
Less than 12 months	643	2,343
12 months or more	857	456
Total	1,500	2,799
Gross Unrealized Losses
Less than 12 months	(7)	(68)
12 months or more	(32)	(42)
Total	(39)	(110)
Mortgage-backed securities
Fair Value
Less than 12 months	593	1,766
12 months or more	2,373	2,203
Total	2,966	3,969
Gross Unrealized Losses
Less than 12 months	(3)	(50)
12 months or more	(333)	(459)
Total	(336)	(509)
Tax-exempt municipal securities
Fair Value
Less than 12 months	51	97
12 months or more	347	405
Total	398	502
Gross Unrealized Losses
Less than 12 months	0	(1)
12 months or more	(14)	(21)
Total	(14)	(22)
Residential
Fair Value
Less than 12 months	10	130
12 months or more	321	343
Total	331	473
Gross Unrealized Losses
Less than 12 months	0	(2)
12 months or more	(46)	(62)
Total	(46)	(64)
Commercial
Fair Value
Less than 12 months	77	58
12 months or more	794	992
Total	871	1,050
Gross Unrealized Losses
Less than 12 months	0	(1)
12 months or more	(47)	(84)
Total	(47)	(85)
Asset-backed securities
Fair Value
Less than 12 months	85	419
12 months or more	263	436
Total	348	855
Gross Unrealized Losses
Less than 12 months	0	(5)
12 months or more	(12)	(19)
Total	(12)	(24)
Corporate debt securities
Fair Value
Less than 12 months	872	2,385
12 months or more	3,785	4,269
Total	4,657	6,654
Gross Unrealized Losses
Less than 12 months	(6)	(51)
12 months or more	(367)	(544)
Total	$ (373)	$ (595)