Business Segment Reporting - Schedule of Selected Financial Data for Our Business Segments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
SUMMARY OF OPERATIONS
Net interest income (TE)	$ 1,193	$ 964	$ 3,448	$ 2,749
Noninterest income	702	(269)	2,060	1,005
Total revenue (TE)	1,895	695	5,508	3,754
Provision for credit losses	107	95	363	296
Personnel expense	742	670	2,127	1,980
Other direct noninterest expense	435	424	1,335	1,336
Support and overhead	0	0	0	0
Income (loss) from continuing operations before income taxes (TE)	611	(494)	1,683	142
Allocated income taxes and TE adjustments	121	(83)	364	61
Income (loss) from continuing operations	490	(411)	1,319	81
Income (loss) from discontinued operations, net of taxes	(1)	1	0	2
NET INCOME (LOSS)	489	(410)	1,319	83
AVERAGE BALANCES
Loans and leases	106,227	106,244	105,439	108,738
Total assets	187,138	187,609	186,679	186,691
Deposits	150,374	147,771	148,793	144,954
Operating Segments | Consumer Bank
SUMMARY OF OPERATIONS
Net interest income (TE)	691	569	2,013	1,614
Noninterest income	244	231	705	691
Total revenue (TE)	935	800	2,718	2,305
Provision for credit losses	40	52	137	83
Personnel expense	230	214	671	634
Other direct noninterest expense	136	137	418	451
Support and overhead	329	298	978	916
Income (loss) from continuing operations before income taxes (TE)	200	99	514	221
Allocated income taxes and TE adjustments	48	24	124	53
Income (loss) from continuing operations	152	75	390	168
Income (loss) from discontinued operations, net of taxes	0	0	0	0
NET INCOME (LOSS)	152	75	390	168
AVERAGE BALANCES
Loans and leases	35,363	38,332	36,101	39,139
Total assets	38,374	41,188	39,107	41,966
Deposits	87,692	86,431	87,998	85,305
Operating Segments | Commercial Bank
SUMMARY OF OPERATIONS
Net interest income (TE)	587	460	1,678	1,268
Noninterest income	427	406	1,252	1,164
Total revenue (TE)	1,014	866	2,930	2,432
Provision for credit losses	68	41	227	231
Personnel expense	200	192	565	521
Other direct noninterest expense	74	74	219	257
Support and overhead	208	178	608	539
Income (loss) from continuing operations before income taxes (TE)	464	381	1,311	884
Allocated income taxes and TE adjustments	97	82	274	175
Income (loss) from continuing operations	367	299	1,037	709
Income (loss) from discontinued operations, net of taxes	0	0	0	0
NET INCOME (LOSS)	367	299	1,037	709
AVERAGE BALANCES
Loans and leases	70,326	67,452	68,835	69,105
Total assets	79,733	76,395	78,320	78,234
Deposits	58,483	58,696	57,272	57,467
Other
SUMMARY OF OPERATIONS
Net interest income (TE)	(85)	(65)	(243)	(133)
Noninterest income	31	(906)	103	(850)
Total revenue (TE)	(54)	(971)	(140)	(983)
Provision for credit losses	(1)	2	(1)	(18)
Personnel expense	312	264	891	825
Other direct noninterest expense	225	213	698	628
Support and overhead	(537)	(476)	(1,586)	(1,455)
Income (loss) from continuing operations before income taxes (TE)	(53)	(974)	(142)	(963)
Allocated income taxes and TE adjustments	(24)	(189)	(34)	(167)
Income (loss) from continuing operations	(29)	(785)	(108)	(796)
Income (loss) from discontinued operations, net of taxes	(1)	1	0	2
NET INCOME (LOSS)	(30)	(784)	(108)	(794)
AVERAGE BALANCES
Loans and leases	538	460	503	494
Total assets	69,031	70,026	69,252	66,491
Deposits	$ 4,199	$ 2,644	$ 3,523	$ 2,182