Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Assets:
Available-for-sale debt and other securities	[1]	$ 50,419	$ 51,503
Equity securities		613	317
Derivative assets		2,677	3,173
Liabilities:
Derivative liabilities		$ 2,999	$ 3,952
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Other assets	Other assets
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Other liabilities	Other liabilities
Residential mortgage
Assets:
Residential mortgage loans		$ 116	$ 123
U.S. Treasury and federal agencies securities
Assets:
Available-for-sale debt and other securities		4,336	2,495
Obligations of states and political subdivisions securities
Assets:
Available-for-sale debt and other securities		2	18
Asset-backed securities and other debt securities
Assets:
Available-for-sale debt and other securities		4,912	5,842
Other securities
Assets:
Available-for-sale debt and other securities		722	874
Liabilities:
FHLB, restricted stock holdings		224	381
FRB, restricted stock holdings		496	491
DTCC, restricted stock holdings		2	2
Level 3     | Interest rate contracts
Assets:
Derivative assets		6	7	$ 12
Liabilities:
Derivative liabilities		6	8	$ 8
Recurring
Assets:
Available-for-sale debt and other securities		49,697	50,629
Trading debt securities		899	414
Equity securities		613	317
Residential mortgage loans held for sale		334	600
Derivative assets		2,677	3,173
Total assets		56,073	57,002
Liabilities:
Derivative liabilities		2,999	3,952
Short positions		107	178
Total liabilities		3,106	4,130
Recurring | Interest rate contracts
Assets:
Derivative assets		983	1,241
Liabilities:
Derivative liabilities		1,213	1,985
Recurring | Foreign exchange contracts
Assets:
Derivative assets		643	454
Liabilities:
Derivative liabilities		600	422
Recurring | Equity contracts
Liabilities:
Derivative liabilities		168	195
Recurring | Commodity contracts
Assets:
Derivative assets		1,051	1,478
Liabilities:
Derivative liabilities		1,018	1,350
Recurring | Servicing rights
Assets:
Servicing rights		1,737	1,746
Recurring | Residential mortgage
Assets:
Residential mortgage loans		116	123
Recurring | U.S. Treasury and federal agencies securities
Assets:
Available-for-sale debt and other securities		4,336	2,495
Trading debt securities		647	45
Liabilities:
Short positions		31	66
Recurring | Obligations of states and political subdivisions securities
Assets:
Available-for-sale debt and other securities		2	18
Trading debt securities		39	14
Recurring | Agency mortgage-backed securities | Residential mortgage
Assets:
Available-for-sale debt and other securities		10,282	11,237
Trading debt securities		6	8
Recurring | Agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities		25,720	26,322
Recurring | Non-agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities		4,445	4,715
Recurring | Asset-backed securities and other debt securities
Assets:
Available-for-sale debt and other securities		4,912	5,842
Trading debt securities		207	347
Liabilities:
Short positions		76	112
Recurring | Level 1
Assets:
Available-for-sale debt and other securities		4,336	2,495
Trading debt securities		640	23
Equity securities		600	306
Residential mortgage loans held for sale		0	0
Derivative assets		205	68
Total assets		5,781	2,892
Liabilities:
Derivative liabilities		33	99
Short positions		31	66
Total liabilities		64	165
Recurring | Level 1 | Interest rate contracts
Assets:
Derivative assets		0	12
Liabilities:
Derivative liabilities		5	7
Recurring | Level 1 | Foreign exchange contracts
Assets:
Derivative assets		0	0
Liabilities:
Derivative liabilities		0	0
Recurring | Level 1 | Equity contracts
Liabilities:
Derivative liabilities		0	0
Recurring | Level 1 | Commodity contracts
Assets:
Derivative assets		205	56
Liabilities:
Derivative liabilities		28	92
Recurring | Level 1 | Servicing rights
Assets:
Servicing rights		0	0
Recurring | Level 1 | Residential mortgage
Assets:
Residential mortgage loans		0	0
Recurring | Level 1 | U.S. Treasury and federal agencies securities
Assets:
Available-for-sale debt and other securities		4,336	2,495
Trading debt securities		640	23
Liabilities:
Short positions		31	66
Recurring | Level 1 | Obligations of states and political subdivisions securities
Assets:
Available-for-sale debt and other securities		0	0
Trading debt securities		0	0
Recurring | Level 1 | Agency mortgage-backed securities | Residential mortgage
Assets:
Available-for-sale debt and other securities		0	0
Trading debt securities		0	0
Recurring | Level 1 | Agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities		0	0
Recurring | Level 1 | Non-agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities		0	0
Recurring | Level 1 | Asset-backed securities and other debt securities
Assets:
Available-for-sale debt and other securities		0	0
Trading debt securities		0	0
Liabilities:
Short positions		0	0
Recurring | Level 2
Assets:
Available-for-sale debt and other securities		45,361	48,134
Trading debt securities		259	391
Equity securities		13	11
Residential mortgage loans held for sale		334	600
Derivative assets		2,466	3,098
Total assets		48,433	52,234
Liabilities:
Derivative liabilities		2,792	3,650
Short positions		76	112
Total liabilities		2,868	3,762
Recurring | Level 2 | Interest rate contracts
Assets:
Derivative assets		977	1,222
Liabilities:
Derivative liabilities		1,202	1,970
Recurring | Level 2 | Foreign exchange contracts
Assets:
Derivative assets		643	454
Liabilities:
Derivative liabilities		600	422
Recurring | Level 2 | Equity contracts
Liabilities:
Derivative liabilities		0	0
Recurring | Level 2 | Commodity contracts
Assets:
Derivative assets		846	1,422
Liabilities:
Derivative liabilities		990	1,258
Recurring | Level 2 | Servicing rights
Assets:
Servicing rights		0	0
Recurring | Level 2 | Residential mortgage
Assets:
Residential mortgage loans		0	0
Recurring | Level 2 | U.S. Treasury and federal agencies securities
Assets:
Available-for-sale debt and other securities		0	0
Trading debt securities		7	22
Liabilities:
Short positions		0	0
Recurring | Level 2 | Obligations of states and political subdivisions securities
Assets:
Available-for-sale debt and other securities		2	18
Trading debt securities		39	14
Recurring | Level 2 | Agency mortgage-backed securities | Residential mortgage
Assets:
Available-for-sale debt and other securities		10,282	11,237
Trading debt securities		6	8
Recurring | Level 2 | Agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities		25,720	26,322
Recurring | Level 2 | Non-agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities		4,445	4,715
Recurring | Level 2 | Asset-backed securities and other debt securities
Assets:
Available-for-sale debt and other securities		4,912	5,842
Trading debt securities		207	347
Liabilities:
Short positions		76	112
Recurring | Level 3
Assets:
Available-for-sale debt and other securities		0	0
Trading debt securities		0	0
Equity securities		0	0
Residential mortgage loans held for sale		0	0
Derivative assets		6	7
Total assets		1,859	1,876
Liabilities:
Derivative liabilities		174	203
Short positions		0	0
Total liabilities		174	203
Recurring | Level 3     | Interest rate contracts
Assets:
Derivative assets		6	7
Liabilities:
Derivative liabilities		6	8
Recurring | Level 3     | Foreign exchange contracts
Assets:
Derivative assets		0	0
Liabilities:
Derivative liabilities		0	0
Recurring | Level 3     | Equity contracts
Liabilities:
Derivative liabilities		168	195
Recurring | Level 3     | Commodity contracts
Assets:
Derivative assets		0	0
Liabilities:
Derivative liabilities		0	0
Recurring | Level 3     | Servicing rights
Assets:
Servicing rights		1,737	1,746
Recurring | Level 3     | Residential mortgage
Assets:
Residential mortgage loans		116	123
Recurring | Level 3     | U.S. Treasury and federal agencies securities
Assets:
Available-for-sale debt and other securities		0	0
Trading debt securities		0	0
Liabilities:
Short positions		0	0
Recurring | Level 3     | Obligations of states and political subdivisions securities
Assets:
Available-for-sale debt and other securities		0	0
Trading debt securities		0	0
Recurring | Level 3     | Agency mortgage-backed securities | Residential mortgage
Assets:
Available-for-sale debt and other securities		0	0
Trading debt securities		0	0
Recurring | Level 3     | Agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities		0	0
Recurring | Level 3     | Non-agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities		0	0
Recurring | Level 3     | Asset-backed securities and other debt securities
Assets:
Available-for-sale debt and other securities		0	0
Trading debt securities		0	0
Liabilities:
Short positions		$ 0	$ 0

[1] Amortized cost of $55,789 and $57,530 at December 31, 2023 and 2022, respectively.