Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Assets:
Equity securities	$ 250	$ 317
Derivative assets	3,303	3,171
Liabilities:
Derivative liabilities	3,772	3,951
Residential Mortgage
Assets:
Residential mortgage loans	113	123	$ 125
Other securities
Liabilities:
FHLB, restricted stock holdings	281	381
FRB, restricted stock holdings	494	491
DTCC, restricted stock holdings	2	2
Level 3 | Interest rate contracts
Assets:
Derivative assets	5		7
Liabilities:
Derivative liabilities	7		$ 14
Recurring
Assets:
Available-for-sale debt and other securities	47,116	50,629
Trading debt securities	1,222	414
Equity securities	250	317
Residential mortgage loans held for sale	497	600
Derivative assets	3,307	3,173
Total assets	54,327	57,002
Liabilities:
Derivative liabilities	3,772	3,952
Short positions	263	178
Total liabilities	4,035	4,130
Recurring | Interest rate contracts
Assets:
Derivative assets	1,486	1,241
Liabilities:
Derivative liabilities	1,911	1,985
Recurring | Foreign exchange contracts
Assets:
Derivative assets	706	454
Liabilities:
Derivative liabilities	644	422
Recurring | Equity contracts
Liabilities:
Derivative liabilities	172	195
Recurring | Commodity contracts
Assets:
Derivative assets	1,115	1,478
Liabilities:
Derivative liabilities	1,045	1,350
Recurring | Servicing rights
Assets:
Servicing rights	1,822	1,746
Recurring | Residential Mortgage
Assets:
Residential mortgage loans	113	123
Recurring | U.S. Treasury and federal agencies securities
Assets:
Available-for-sale debt and other securities	3,462	2,495
Trading debt securities	641	45
Liabilities:
Short positions	108	66
Recurring | Obligations of states and political subdivisions securities
Assets:
Available-for-sale debt and other securities	2	18
Trading debt securities	43	14
Recurring | Agency mortgage-backed securities | Residential Mortgage
Assets:
Available-for-sale debt and other securities	9,876	11,237
Trading debt securities	7	8
Recurring | Agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities	24,461	26,322
Recurring | Non-agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities	4,325	4,715
Recurring | Asset-backed securities and other debt securities
Assets:
Available-for-sale debt and other securities	4,990	5,842
Trading debt securities	531	347
Liabilities:
Short positions	155	112
Recurring | Level 1
Assets:
Available-for-sale debt and other securities	3,462	2,495
Trading debt securities	610	23
Equity securities	238	306
Residential mortgage loans held for sale	0	0
Derivative assets	103	68
Total assets	4,413	2,892
Liabilities:
Derivative liabilities	142	99
Short positions	108	66
Total liabilities	250	165
Recurring | Level 1 | Interest rate contracts
Assets:
Derivative assets	14	12
Liabilities:
Derivative liabilities	1	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	89	56
Liabilities:
Derivative liabilities	141	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	3,462	2,495
Trading debt securities	610	23
Liabilities:
Short positions	108	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	43,654	48,134
Trading debt securities	612	391
Equity securities	12	11
Residential mortgage loans held for sale	497	600
Derivative assets	3,199	3,098
Total assets	47,974	52,234
Liabilities:
Derivative liabilities	3,451	3,650
Short positions	155	112
Total liabilities	3,606	3,762
Recurring | Level 2 | Interest rate contracts
Assets:
Derivative assets	1,467	1,222
Liabilities:
Derivative liabilities	1,903	1,970
Recurring | Level 2 | Foreign exchange contracts
Assets:
Derivative assets	706	454
Liabilities:
Derivative liabilities	644	422
Recurring | Level 2 | Equity contracts
Liabilities:
Derivative liabilities	0	0
Recurring | Level 2 | Commodity contracts
Assets:
Derivative assets	1,026	1,422
Liabilities:
Derivative liabilities	904	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	31	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	43	14
Recurring | Level 2 | Agency mortgage-backed securities | Residential Mortgage
Assets:
Available-for-sale debt and other securities	9,876	11,237
Trading debt securities	7	8
Recurring | Level 2 | Agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities	24,461	26,322
Recurring | Level 2 | Non-agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities	4,325	4,715
Recurring | Level 2 | Asset-backed securities and other debt securities
Assets:
Available-for-sale debt and other securities	4,990	5,842
Trading debt securities	531	347
Liabilities:
Short positions	155	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	5	7
Total assets	1,940	1,876
Liabilities:
Derivative liabilities	179	203
Short positions	0	0
Total liabilities	179	203
Recurring | Level 3 | Interest rate contracts
Assets:
Derivative assets	5	7
Liabilities:
Derivative liabilities	7	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	172	195
Recurring | Level 3 | Commodity contracts
Assets:
Derivative assets	0	0
Liabilities:
Derivative liabilities	0	0
Recurring | Level 3 | Servicing rights
Assets:
Servicing rights	1,822	1,746
Recurring | Level 3 | Residential Mortgage
Assets:
Residential mortgage loans	113	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