INVESTMENT SECURITIES AND OTHER SECURITIES - Continuous Unrealized Loss Position (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Available-for-sale securities:
Less than 12 months, fair value	$ 1,198	$ 4,726
Less than 12 months, gross unrealized losses	(14)	(74)
12 months or longer, fair value	16,499	18,038
12 months or longer, gross unrealized losses	(2,430)	(3,409)
Total, fair value	17,697	22,764
Total, gross unrealized losses	(2,444)	(3,483)
Held-to-maturity securities:
Less than 12 months, fair value	48	1,843
Less than 12 months, fair value	0	(25)
12 months or longer, fair value	11,079	11,495
12 months or longer, gross unrealized losses	(1,647)	(2,260)
Total held-to-maturity securities	11,127	13,338
Total, gross unrealized losses	(1,647)	(2,285)
U.S. Treasury
Available-for-sale securities:
Less than 12 months, fair value	0	3,153
Less than 12 months, gross unrealized losses	0	(43)
12 months or longer, fair value	439	0
12 months or longer, gross unrealized losses	0	0
Total, fair value	439	3,153
Total, gross unrealized losses	0	(43)
Held-to-maturity securities:
Less than 12 months, fair value	0	1,581
Less than 12 months, fair value	0	(22)
12 months or longer, fair value	289	0
12 months or longer, gross unrealized losses	0	0
Total held-to-maturity securities	289	1,581
Total, gross unrealized losses	0	(22)
US Treasury and Government
Available-for-sale securities:
Less than 12 months, fair value	144	3,692
Less than 12 months, gross unrealized losses	0	(49)
12 months or longer, fair value	14,145	14,299
12 months or longer, gross unrealized losses	(2,333)	(3,171)
Total, fair value	14,289	17,991
Total, gross unrealized losses	(2,333)	(3,220)
Held-to-maturity securities:
Less than 12 months, fair value	48	1,843
Less than 12 months, fair value	0	(25)
12 months or longer, fair value	11,078	11,494
12 months or longer, gross unrealized losses	(1,647)	(2,260)
Total held-to-maturity securities	11,126	13,337
Total, gross unrealized losses	(1,647)	(2,285)
Residential MBS
Available-for-sale securities:
Less than 12 months, fair value	55	275
Less than 12 months, gross unrealized losses	0	(5)
12 months or longer, fair value	9,185	9,676
12 months or longer, gross unrealized losses	(1,365)	(1,966)
Total, fair value	9,240	9,951
Total, gross unrealized losses	(1,365)	(1,971)
Held-to-maturity securities:
Less than 12 months, fair value	0	99
Less than 12 months, fair value	0	(2)
12 months or longer, fair value	6,694	7,097
12 months or longer, gross unrealized losses	(941)	(1,334)
Total held-to-maturity securities	6,694	7,196
Total, gross unrealized losses	(941)	(1,336)
Residential CMO
Available-for-sale securities:
Less than 12 months, fair value	51	243
Less than 12 months, gross unrealized losses	0	(1)
12 months or longer, fair value	2,665	2,802
12 months or longer, gross unrealized losses	(308)	(433)
Total, fair value	2,716	3,045
Total, gross unrealized losses	(308)	(434)
Held-to-maturity securities:
Less than 12 months, fair value	48	163
Less than 12 months, fair value	0	(1)
12 months or longer, fair value	2,956	3,152
12 months or longer, gross unrealized losses	(520)	(690)
Total held-to-maturity securities	3,004	3,315
Total, gross unrealized losses	(520)	(691)
Commercial MBS
Available-for-sale securities:
Less than 12 months, fair value	23	0
Less than 12 months, gross unrealized losses	0	0
12 months or longer, fair value	1,782	1,752
12 months or longer, gross unrealized losses	(657)	(767)
Total, fair value	1,805	1,752
Total, gross unrealized losses	(657)	(767)
Held-to-maturity securities:
Less than 12 months, fair value	0	0
Less than 12 months, fair value	0	0
12 months or longer, fair value	1,094	1,176
12 months or longer, gross unrealized losses	(184)	(231)
Total held-to-maturity securities	1,094	1,176
Total, gross unrealized losses	(184)	(231)
Other agencies
Available-for-sale securities:
Less than 12 months, fair value	15	21
Less than 12 months, gross unrealized losses	0	0
12 months or longer, fair value	74	69
12 months or longer, gross unrealized losses	(3)	(5)
Total, fair value	89	90
Total, gross unrealized losses	(3)	(5)
Held-to-maturity securities:
Less than 12 months, fair value	0	0
Less than 12 months, fair value	0	0
12 months or longer, fair value	45	69
12 months or longer, gross unrealized losses	(2)	(5)
Total held-to-maturity securities	45	69
Total, gross unrealized losses	(2)	(5)
Municipal securities
Available-for-sale securities:
Less than 12 months, fair value	1,043	985
Less than 12 months, gross unrealized losses	(14)	(25)
12 months or longer, fair value	1,892	2,336
12 months or longer, gross unrealized losses	(67)	(107)
Total, fair value	2,935	3,321
Total, gross unrealized losses	(81)	(132)
Held-to-maturity securities:
Less than 12 months, fair value	0	0
Less than 12 months, fair value	0	0
12 months or longer, fair value	1	1
12 months or longer, gross unrealized losses	0	0
Total held-to-maturity securities	1	1
Total, gross unrealized losses	0	0
Corporate debt
Available-for-sale securities:
Less than 12 months, fair value	2	0
Less than 12 months, gross unrealized losses	0	0
12 months or longer, fair value	176	1,053
12 months or longer, gross unrealized losses	(15)	(102)
Total, fair value	178	1,053
Total, gross unrealized losses	(15)	(102)
Asset-backed securities
Available-for-sale securities:
Less than 12 months, fair value	9	49
Less than 12 months, gross unrealized losses	0	0
12 months or longer, fair value	207	263
12 months or longer, gross unrealized losses	(8)	(19)
Total, fair value	216	312
Total, gross unrealized losses	(8)	(19)
Private-label CMO
Available-for-sale securities:
Less than 12 months, fair value	0	0
Less than 12 months, gross unrealized losses	0	0
12 months or longer, fair value	79	87
12 months or longer, gross unrealized losses	(7)	(10)
Total, fair value	79	87
Total, gross unrealized losses	$ (7)	$ (10)