Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024	Sep. 30, 2024
Assets:
Available-for-sale debt and other securities:	$ 36,461	$ 39,547
Equity securities	287	341
Derivative assets	1,837	2,472
Liabilities:
Derivative Liabilities	2,055	2,798
Residential Mortgage
Assets:
Residential mortgage loans	107	108	$ 114
U.S. Treasury and federal agencies securities
Assets:
Available-for-sale debt and other securities:	2,105	4,360
Asset-backed securities and other debt securities
Assets:
Available-for-sale debt and other securities:	2,442	3,729
Other securities
Assets:
Available-for-sale debt and other securities:	868	778
Liabilities:
FHLB, restricted stock holdings	362	276
FRB, restricted stock holdings	504	500
DTCC, restricted stock holdings	2	2
Level 3 | Interest rate contracts
Assets:
Derivative assets	8		7
Liabilities:
Derivative Liabilities	5		$ 5
Recurring
Assets:
Available-for-sale debt and other securities:	35,593	38,769
Trading debt securities	1,266	1,185
Equity securities	287	341
Residential mortgage loans held for sale	565	574
Derivative assets	1,837	2,472
Total assets	41,256	45,153
Liabilities:
Derivative Liabilities	2,055	2,798
Short positions	419	316
Total liabilities	2,474	3,114
Recurring | Interest rate contracts
Assets:
Derivative assets	502	730
Liabilities:
Derivative Liabilities	605	944
Recurring | Foreign exchange contracts
Assets:
Derivative assets	668	1,167
Liabilities:
Derivative Liabilities	628	1,120
Recurring | Equity contracts
Liabilities:
Derivative Liabilities	150	170
Recurring | Commodity contracts
Assets:
Derivative assets	667	575
Liabilities:
Derivative Liabilities	672	564
Recurring | Servicing rights
Assets:
Servicing rights	1,601	1,704
Recurring | Residential Mortgage
Assets:
Residential mortgage loans	107	108
Recurring | U.S. Treasury and federal agencies securities
Assets:
Available-for-sale debt and other securities:	2,105	4,360
Trading debt securities	576	626
Liabilities:
Short positions	114	139
Recurring | Obligations of states and political subdivisions securities
Assets:
Trading debt securities	58	120
Recurring | Agency mortgage-backed securities | Residential Mortgage
Assets:
Available-for-sale debt and other securities:	7,535	5,681
Trading debt securities	39	10
Recurring | Agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities:	20,564	20,832
Recurring | Non-agency commercial mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities:	2,947	4,167
Recurring | Asset-backed securities and other debt securities
Assets:
Available-for-sale debt and other securities:	2,442	3,729
Trading debt securities	593	429
Liabilities:
Short positions	276	156
Recurring | Equity securities
Liabilities:
Short positions	29	21
Recurring | Level 1
Assets:
Available-for-sale debt and other securities:	2,105	4,360
Trading debt securities	558	591
Equity securities	270	307
Residential mortgage loans held for sale	0	0
Derivative assets	167	82
Total assets	3,100	5,340
Liabilities:
Derivative Liabilities	59	57
Short positions	142	160
Total liabilities	201	217
Recurring | Level 1 | Interest rate contracts
Assets:
Derivative assets	3	7
Liabilities:
Derivative Liabilities	5	0
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	164	75
Liabilities:
Derivative Liabilities	54	57
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:	2,105	4,360
Trading debt securities	558	591
Liabilities:
Short positions	113	139
Recurring | Level 1 | Obligations of states and political subdivisions securities
Assets:
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 commercial 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 1 | Equity securities
Liabilities:
Short positions	29	21
Recurring | Level 2
Assets:
Available-for-sale debt and other securities:	33,488	34,409
Trading debt securities	708	594
Equity securities	17	34
Residential mortgage loans held for sale	565	574
Derivative assets	1,662	2,388
Total assets	36,440	37,999
Liabilities:
Derivative Liabilities	1,841	2,566
Short positions	277	156
Total liabilities	2,118	2,722
Recurring | Level 2 | Interest rate contracts
Assets:
Derivative assets	491	721
Liabilities:
Derivative Liabilities	595	939
Recurring | Level 2 | Foreign exchange contracts
Assets:
Derivative assets	668	1,167
Liabilities:
Derivative Liabilities	628	1,120
Recurring | Level 2 | Equity contracts
Liabilities:
Derivative Liabilities	0	0
Recurring | Level 2 | Commodity contracts
Assets:
Derivative assets	503	500
Liabilities:
Derivative Liabilities	618	507
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	18	35
Liabilities:
Short positions	1	0
Recurring | Level 2 | Obligations of states and political subdivisions securities
Assets:
Trading debt securities	58	120
Recurring | Level 2 | Agency mortgage-backed securities | Residential Mortgage
Assets:
Available-for-sale debt and other securities:	7,535	5,681
Trading debt securities	39	10
Recurring | Level 2 | Agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities:	20,564	20,832
Recurring | Level 2 | Non-agency commercial mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities:	2,947	4,167
Recurring | Level 2 | Asset-backed securities and other debt securities
Assets:
Available-for-sale debt and other securities:	2,442	3,729
Trading debt securities	593	429
Liabilities:
Short positions	276	156
Recurring | Level 2 | Equity securities
Liabilities:
Short positions	0	0
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	8	2
Total assets	1,716	1,814
Liabilities:
Derivative Liabilities	155	175
Short positions	0	0
Total liabilities	155	175
Recurring | Level 3 | Interest rate contracts
Assets:
Derivative assets	8	2
Liabilities:
Derivative Liabilities	5	5
Recurring | Level 3 | Foreign exchange contracts
Assets:
Derivative assets	0	0
Liabilities:
Derivative Liabilities	0	0
Recurring | Level 3 | Equity contracts
Liabilities:
Derivative Liabilities	150	170
Recurring | Level 3 | Commodity contracts
Assets:
Derivative assets	0	0
Liabilities:
Derivative Liabilities	0	0
Recurring | Level 3 | Servicing rights
Assets:
Servicing rights	1,601	1,704
Recurring | Level 3 | Residential Mortgage
Assets:
Residential mortgage loans	107	108
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:
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 commercial 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
Recurring | Level 3 | Equity securities
Liabilities:
Short positions	$ 0	$ 0