Business Segments - Summary of Accounting Change Impact (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Profit Before  Income Tax	$ 94	$ 27	$ (170)
Segment total assets	(13,260)	(19,647)	(17,581)
Goodwill	458	458	458
Operating Segments
Segment Reporting Information [Line Items]
Profit Before  Income Tax	1,324	1,020	658
Segment total assets	185,670	190,378	185,578
Segment total deposits	119,621	114,094	116,892
IWPB | Operating Segments
Segment Reporting Information [Line Items]
Profit Before  Income Tax	188	122	270
Segment total assets	36,366	39,991	44,031
Segment total deposits	26,103	26,676	29,611
CIB | Operating Segments
Segment Reporting Information [Line Items]
Profit Before  Income Tax	1,288	1,062	755
Segment total assets	144,394	146,541	138,684
Segment total deposits	93,518	87,418	87,281
CC | Operating Segments
Segment Reporting Information [Line Items]
Profit Before  Income Tax	(152)	(164)	(367)
Segment total assets	4,910	3,846	2,863
Segment total deposits	$ 0	0	0
As Previously Reported | IWPB | Operating Segments
Segment Reporting Information [Line Items]
Profit Before  Income Tax		122	270
Segment total assets		39,991	44,031
Segment total deposits		26,676	29,611
As Previously Reported | CMB | Operating Segments
Segment Reporting Information [Line Items]
Profit Before  Income Tax		654	590
Segment total assets		55,607	52,484
Segment total deposits		44,192	43,667
Goodwill		358	358
As Previously Reported | GB | Operating Segments
Segment Reporting Information [Line Items]
Profit Before  Income Tax		367	176
Segment total assets		9,658	10,231
Segment total deposits		41,159	40,166
As Previously Reported | MSS | Operating Segments
Segment Reporting Information [Line Items]
Profit Before  Income Tax		81	100
Segment total assets		41,213	38,811
Segment total deposits		1,419	767
As Previously Reported | GBM Other | Operating Segments
Segment Reporting Information [Line Items]
Profit Before  Income Tax		(40)	(111)
Segment total assets		40,063	37,158
Segment total deposits		648	2,681
As Previously Reported | CC | Operating Segments
Segment Reporting Information [Line Items]
Profit Before  Income Tax		(164)	(367)
Segment total assets		3,846	2,863
Segment total deposits		$ 0	$ 0