Loans and Allowance for Credit Losses - Loans by Portfolio Class and Internal Credit Quality Rating (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Loans by origination year
Total loans	$ 382,517		$ 382,517		$ 379,832
Total outstanding commitments	819,484		819,484		792,471
Modified loans	1,244	$ 1,540	3,349	$ 3,661
Pass
Loans by origination year
Total loans	373,496		373,496		369,052
Total outstanding commitments	807,499		807,499		778,155
Total Criticized
Loans by origination year
Total loans	9,021		9,021		10,780
Total outstanding commitments	11,985		11,985		14,316
Special Mention
Loans by origination year
Total loans	2,132		2,132		2,424
Total outstanding commitments	3,212		3,212		3,875
Classified
Loans by origination year
Total loans	6,889		6,889		8,356
Total outstanding commitments	8,773		8,773		10,441
Loans purchased from GNMA mortgage pools
Loans by origination year
Modified loans	666	588	1,677	1,640
Commercial | Commercial
Loans by origination year
Originated in 2025/2024	53,498		53,498		59,115
Originated in 2024/2023	33,770		33,770		19,865
Originated in 2023/2022	9,599		9,599		20,319
Originated in 2022/2021	12,471		12,471		4,829
Originated in 2021	3,064		3,064
Originated prior to 2021	4,787		4,787
Originated prior to 2021					7,031
Revolving	31,225		31,225		28,325
Total loans	148,414		148,414		139,484
Modified loans	174	318	455	666
Commercial | Commercial | Pass
Loans by origination year
Originated in 2025/2024	52,825		52,825		57,578
Originated in 2024/2023	32,628		32,628		19,128
Originated in 2023/2022	9,151		9,151		19,718
Originated in 2022/2021	12,045		12,045		4,677
Originated in 2021	3,028		3,028
Originated prior to 2021	4,642		4,642
Originated prior to 2021					6,812
Revolving	30,209		30,209		27,344
Total loans	144,528		144,528		135,257
Commercial | Commercial | Total Criticized
Loans by origination year
Originated in 2025/2024	673		673		1,537
Originated in 2024/2023	1,142		1,142		737
Originated in 2023/2022	448		448		601
Originated in 2022/2021	426		426		152
Originated in 2021	36		36
Originated prior to 2021	145		145
Originated prior to 2021					219
Revolving	1,016		1,016		981
Total loans	3,886		3,886		4,227
Commercial | Commercial | Special Mention
Loans by origination year
Originated in 2025/2024	208		208		503
Originated in 2024/2023	384		384		173
Originated in 2023/2022	65		65		231
Originated in 2022/2021	24		24		60
Originated in 2021	4		4
Originated prior to 2021	61		61
Originated prior to 2021					76
Revolving	576		576		169
Total loans	1,322		1,322		1,212
Commercial | Commercial | Classified
Loans by origination year
Originated in 2025/2024	465		465		1,034
Originated in 2024/2023	758		758		564
Originated in 2023/2022	383		383		370
Originated in 2022/2021	402		402		92
Originated in 2021	32		32
Originated prior to 2021	84		84
Originated prior to 2021					143
Revolving	440		440		812
Total loans	2,564		2,564		3,015
Commercial | Commercial real estate
Loans by origination year
Originated in 2025/2024	11,475		11,475		11,685
Originated in 2024/2023	7,854		7,854		6,015
Originated in 2023/2022	4,719		4,719		10,621
Originated in 2022/2021	7,515		7,515		6,811
Originated in 2021	5,169		5,169
Originated prior to 2021	9,530		9,530
Originated prior to 2021					11,578
Revolving	1,978		1,978		2,146
Revolving converted to term	4		4		3
Total loans	48,244		48,244		48,859
Modified loans	179	428	444	837
Commercial | Commercial real estate | Pass
Loans by origination year
Originated in 2025/2024	10,556		10,556		9,652
Originated in 2024/2023	7,222		7,222		5,213
Originated in 2023/2022	4,052		4,052		9,047
Originated in 2022/2021	6,568		6,568		6,515
Originated in 2021	4,938		4,938
Originated prior to 2021	8,908		8,908
Originated prior to 2021					10,822
Revolving	1,920		1,920		2,078
Revolving converted to term	4		4		3
Total loans	44,168		44,168		43,330
Commercial | Commercial real estate | Total Criticized
Loans by origination year
Originated in 2025/2024	919		919		2,033
Originated in 2024/2023	632		632		802
Originated in 2023/2022	667		667		1,574
Originated in 2022/2021	947		947		296
Originated in 2021	231		231
Originated prior to 2021	622		622
Originated prior to 2021					756
Revolving	58		58		68
Revolving converted to term	0		0		0
Total loans	4,076		4,076		5,529
Commercial | Commercial real estate | Special Mention
Loans by origination year
Originated in 2025/2024	142		142		261
Originated in 2024/2023	58		58		42
Originated in 2023/2022	55		55		661
Originated in 2022/2021	272		272		100
Originated in 2021	87		87
Originated prior to 2021	149		149
Originated prior to 2021					148
Revolving	47		47		0
Revolving converted to term	0		0		0
Total loans	810		810		1,212
Commercial | Commercial real estate | Classified
Loans by origination year
Originated in 2025/2024	777		777		1,772
Originated in 2024/2023	574		574		760
Originated in 2023/2022	612		612		913
Originated in 2022/2021	675		675		196
Originated in 2021	144		144
Originated prior to 2021	473		473
Originated prior to 2021					608
Revolving	11		11		68
Revolving converted to term	0		0		0
Total loans	3,266		3,266		4,317
Consumer | Residential mortgages
Loans by origination year
Originated in 2025/2024	8,077		8,077		10,291
Originated in 2024/2023	8,672		8,672		8,775
Originated in 2023/2022	8,168		8,168		28,527
Originated in 2022/2021	24,920		24,920		34,729
Originated in 2021	31,361		31,361
Originated prior to 2021	33,847		33,847
Originated prior to 2021					36,491
Revolving	1		1		0
Total loans	115,046		115,046		118,813
Modified loans	46	31	330	77
Consumer | Residential mortgages | Pass
Loans by origination year
Originated in 2025/2024	8,076		8,076		10,291
Originated in 2024/2023	8,660		8,660		8,764
Originated in 2023/2022	8,137		8,137		28,484
Originated in 2022/2021	24,860		24,860		34,694
Originated in 2021	31,300		31,300
Originated prior to 2021	33,556		33,556
Originated prior to 2021					36,211
Revolving	1		1		0
Total loans	114,590		114,590		118,444
Consumer | Residential mortgages | Total Criticized
Loans by origination year
Originated in 2025/2024	1		1		0
Originated in 2024/2023	12		12		11
Originated in 2023/2022	31		31		43
Originated in 2022/2021	60		60		35
Originated in 2021	61		61
Originated prior to 2021	291		291
Originated prior to 2021					280
Revolving	0		0		0
Total loans	456		456		369
Consumer | Residential mortgages | Special Mention
Loans by origination year
Originated in 2025/2024	0		0		0
Originated in 2024/2023	0		0		0
Originated in 2023/2022	0		0		0
Originated in 2022/2021	0		0		0
Originated in 2021	0		0
Originated prior to 2021	0		0
Originated prior to 2021					0
Revolving	0		0		0
Total loans	0		0		0
Consumer | Residential mortgages | Classified
Loans by origination year
Originated in 2025/2024	1		1		0
Originated in 2024/2023	12		12		11
Originated in 2023/2022	31		31		43
Originated in 2022/2021	60		60		35
Originated in 2021	61		61
Originated prior to 2021	291		291
Originated prior to 2021					280
Revolving	0		0		0
Total loans	456		456		369
Consumer | Residential mortgages | Loans purchased from GNMA mortgage pools | Pass
Loans by origination year
Loans 90 days or more past due	2,400		2,400		2,300
Modified loans			1,500		1,400
Consumer | Credit card
Loans by origination year
Total loans	30,594		30,594		30,350
Modified loans	147	135	355	332
Consumer | Credit card | Pass
Loans by origination year
Total loans	30,210		30,210		29,915
Consumer | Credit card | Total Criticized
Loans by origination year
Total loans	384		384		435
Consumer | Credit card | Special Mention
Loans by origination year
Total loans	0		0		0
Consumer | Credit card | Classified
Loans by origination year
Total loans	384		384		435
Consumer | Other retail
Loans by origination year
Originated in 2025/2024	4,896		4,896		7,401
Originated in 2024/2023	5,421		5,421		3,975
Originated in 2023/2022	2,981		2,981		4,096
Originated in 2022/2021	2,904		2,904		6,551
Originated in 2021	4,441		4,441
Originated prior to 2021	4,255		4,255
Originated prior to 2021					5,564
Revolving	14,488		14,488		13,966
Revolving converted to term	833		833		773
Total loans	40,219		40,219		42,326
Modified loans	32	$ 40	88	$ 109
Consumer | Other retail | Pass
Loans by origination year
Originated in 2025/2024	4,894		4,894		7,398
Originated in 2024/2023	5,412		5,412		3,966
Originated in 2023/2022	2,971		2,971		4,085
Originated in 2022/2021	2,893		2,893		6,537
Originated in 2021	4,431		4,431
Originated prior to 2021	4,238		4,238
Originated prior to 2021					5,543
Revolving	14,369		14,369		13,846
Revolving converted to term	792		792		731
Total loans	40,000		40,000		42,106
Consumer | Other retail | Total Criticized
Loans by origination year
Originated in 2025/2024	2		2		3
Originated in 2024/2023	9		9		9
Originated in 2023/2022	10		10		11
Originated in 2022/2021	11		11		14
Originated in 2021	10		10
Originated prior to 2021	17		17
Originated prior to 2021					21
Revolving	119		119		120
Revolving converted to term	41		41		42
Total loans	219		219		220
Consumer | Other retail | Special Mention
Loans by origination year
Originated in 2025/2024	0		0		0
Originated in 2024/2023	0		0		0
Originated in 2023/2022	0		0		0
Originated in 2022/2021	0		0		0
Originated in 2021	0		0
Originated prior to 2021	0		0
Originated prior to 2021					0
Revolving	0		0		0
Revolving converted to term	0		0		0
Total loans	0		0		0
Consumer | Other retail | Classified
Loans by origination year
Originated in 2025/2024	2		2		3
Originated in 2024/2023	9		9		9
Originated in 2023/2022	10		10		11
Originated in 2022/2021	11		11		14
Originated in 2021	10		10
Originated prior to 2021	17		17
Originated prior to 2021					21
Revolving	119		119		120
Revolving converted to term	41		41		42
Total loans	$ 219		$ 219		$ 220