Loans and Allowance for Credit Losses - Loans Modified by Modification Type (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Financing Receivable, Modified [Line Items]
Modifications	$ 1,468	$ 1,631	$ 2,686	$ 2,848
Percent of Class Total	0.40%	0.40%	0.70%	0.80%
Interest Rate Reduction
Financing Receivable, Modified [Line Items]
Modifications	$ 149	$ 219	$ 291	$ 355
Payment Delay
Financing Receivable, Modified [Line Items]
Modifications	456	483	999	937
Term Extension
Financing Receivable, Modified [Line Items]
Modifications	607	793	999	1,335
Multiple Modifications
Financing Receivable, Modified [Line Items]
Modifications	256	136	397	221
Payment Delay and Term Extension
Financing Receivable, Modified [Line Items]
Modifications	97	111	166	189
Interest Rate Reduction and Term Extension
Financing Receivable, Modified [Line Items]
Modifications	134	17	191	20
Interest Rate Reduction, Payment Delay and Term Extension
Financing Receivable, Modified [Line Items]
Modifications	25	8	40	12
Total loans, excluding loans purchased from GNMA mortgage pools
Financing Receivable, Modified [Line Items]
Modifications	$ 783	$ 926	$ 1,473	$ 1,562
Percent of Class Total	0.20%	0.20%	0.40%	0.40%
Total loans, excluding loans purchased from GNMA mortgage pools | Interest Rate Reduction
Financing Receivable, Modified [Line Items]
Modifications	$ 149	$ 219	$ 291	$ 354
Total loans, excluding loans purchased from GNMA mortgage pools | Payment Delay
Financing Receivable, Modified [Line Items]
Modifications	81	9	303	29
Total loans, excluding loans purchased from GNMA mortgage pools | Term Extension
Financing Receivable, Modified [Line Items]
Modifications	469	684	766	1,162
Total loans, excluding loans purchased from GNMA mortgage pools | Multiple Modifications
Financing Receivable, Modified [Line Items]
Modifications	84	14	113	17
Loans purchased from GNMA mortgage pools
Financing Receivable, Modified [Line Items]
Modifications	$ 685	$ 705	$ 1,213	$ 1,286
Percent of Class Total	0.60%	0.60%	1.10%	1.10%
Loans purchased from GNMA mortgage pools | Interest Rate Reduction
Financing Receivable, Modified [Line Items]
Modifications	$ 0	$ 0	$ 0	$ 1
Loans purchased from GNMA mortgage pools | Payment Delay
Financing Receivable, Modified [Line Items]
Modifications	375	474	696	908
Loans purchased from GNMA mortgage pools | Term Extension
Financing Receivable, Modified [Line Items]
Modifications	138	109	233	173
Loans purchased from GNMA mortgage pools | Multiple Modifications
Financing Receivable, Modified [Line Items]
Modifications	172	122	284	204
Commercial | Commercial
Financing Receivable, Modified [Line Items]
Modifications	$ 251	$ 276	$ 395	$ 496
Percent of Class Total	0.20%	0.20%	0.30%	0.40%
Commercial | Commercial | Interest Rate Reduction
Financing Receivable, Modified [Line Items]
Modifications	$ 24	$ 23	$ 46	$ 44
Commercial | Commercial | Payment Delay
Financing Receivable, Modified [Line Items]
Modifications	0	0	2	0
Commercial | Commercial | Term Extension
Financing Receivable, Modified [Line Items]
Modifications	158	253	260	452
Commercial | Commercial | Multiple Modifications
Financing Receivable, Modified [Line Items]
Modifications	69	0	87	0
Commercial | Commercial real estate
Financing Receivable, Modified [Line Items]
Modifications	$ 283	$ 476	$ 453	$ 714
Percent of Class Total	0.60%	0.90%	0.90%	1.40%
Commercial | Commercial real estate | Interest Rate Reduction
Financing Receivable, Modified [Line Items]
Modifications	$ 0	$ 78	$ 0	$ 78
Commercial | Commercial real estate | Payment Delay
Financing Receivable, Modified [Line Items]
Modifications	0	0	0	0
Commercial | Commercial real estate | Term Extension
Financing Receivable, Modified [Line Items]
Modifications	283	391	451	629
Commercial | Commercial real estate | Multiple Modifications
Financing Receivable, Modified [Line Items]
Modifications	0	7	2	7
Consumer | Residential mortgages
Financing Receivable, Modified [Line Items]
Modifications	$ 92	$ 22	$ 315	$ 49
Percent of Class Total	0.10%	0.00%	0.30%	0.00%
Consumer | Residential mortgages | Interest Rate Reduction
Financing Receivable, Modified [Line Items]
Modifications	$ 0	$ 0	$ 0	$ 0
Consumer | Residential mortgages | Payment Delay
Financing Receivable, Modified [Line Items]
Modifications	77	9	293	28
Consumer | Residential mortgages | Term Extension
Financing Receivable, Modified [Line Items]
Modifications	3	7	5	12
Consumer | Residential mortgages | Multiple Modifications
Financing Receivable, Modified [Line Items]
Modifications	12	6	17	9
Consumer | Credit card
Financing Receivable, Modified [Line Items]
Modifications	$ 123	$ 116	$ 244	$ 228
Percent of Class Total	0.40%	0.40%	0.80%	0.80%
Consumer | Credit card | Interest Rate Reduction
Financing Receivable, Modified [Line Items]
Modifications	$ 123	$ 116	$ 241	$ 228
Consumer | Credit card | Payment Delay
Financing Receivable, Modified [Line Items]
Modifications	0	0	3	0
Consumer | Credit card | Term Extension
Financing Receivable, Modified [Line Items]
Modifications	0	0	0	0
Consumer | Credit card | Multiple Modifications
Financing Receivable, Modified [Line Items]
Modifications	0	0	0	0
Consumer | Other retail
Financing Receivable, Modified [Line Items]
Modifications	$ 34	$ 36	$ 66	$ 75
Percent of Class Total	0.10%	0.10%	0.20%	0.20%
Consumer | Other retail | Interest Rate Reduction
Financing Receivable, Modified [Line Items]
Modifications	$ 2	$ 2	$ 4	$ 4
Consumer | Other retail | Payment Delay
Financing Receivable, Modified [Line Items]
Modifications	4	0	5	1
Consumer | Other retail | Term Extension
Financing Receivable, Modified [Line Items]
Modifications	25	33	50	69
Consumer | Other retail | Multiple Modifications
Financing Receivable, Modified [Line Items]
Modifications	$ 3	$ 1	$ 7	$ 1