Variable Interest Entities and Securitizations - Carrying Amount of Consolidated and Unconsolidated VIEs (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Variable Interest Entity [Line Items]
Carrying Amount of Assets	$ 481,720	$ 478,464
Carrying Amount of Liabilities	423,919	420,375
Maximum Exposure to Loss	6,061	6,175
Consolidated
Variable Interest Entity [Line Items]
Carrying Amount of Assets	32,051	33,288
Carrying Amount of Liabilities	18,380	18,746
Unconsolidated
Variable Interest Entity [Line Items]
Carrying Amount of Assets	6,061	6,175
Carrying Amount of Liabilities	2,001	2,085
Affordable housing entities
Variable Interest Entity [Line Items]
Maximum Exposure to Loss	5,650	5,726
VIE, nonconsolidated, carrying amount of assets included in certain investment structures	2,600	2,600
VIE, nonconsolidated, carrying amount of liabilities included in certain investment structures	984	989
Affordable housing entities | Consolidated
Variable Interest Entity [Line Items]
Carrying Amount of Assets	295	297
Carrying Amount of Liabilities	23	23
Affordable housing entities | Unconsolidated
Variable Interest Entity [Line Items]
Carrying Amount of Assets	5,650	5,726
Carrying Amount of Liabilities	2,001	2,085
Entities that provide capital to low-income and rural communities
Variable Interest Entity [Line Items]
Maximum Exposure to Loss	0	0
Entities that provide capital to low-income and rural communities | Consolidated
Variable Interest Entity [Line Items]
Carrying Amount of Assets	2,872	2,498
Carrying Amount of Liabilities	10	10
Entities that provide capital to low-income and rural communities | Unconsolidated
Variable Interest Entity [Line Items]
Carrying Amount of Assets	0	0
Carrying Amount of Liabilities	0	0
Other
Variable Interest Entity [Line Items]
Maximum Exposure to Loss	411	449
Other | Consolidated
Variable Interest Entity [Line Items]
Carrying Amount of Assets	0	0
Carrying Amount of Liabilities	0	0
Other | Unconsolidated
Variable Interest Entity [Line Items]
Carrying Amount of Assets	411	449
Carrying Amount of Liabilities	0	0
Total other VIEs
Variable Interest Entity [Line Items]
Maximum Exposure to Loss	6,061	6,175
Total other VIEs | Consolidated
Variable Interest Entity [Line Items]
Carrying Amount of Assets	3,167	2,795
Carrying Amount of Liabilities	33	33
Total other VIEs | Unconsolidated
Variable Interest Entity [Line Items]
Carrying Amount of Assets	6,061	6,175
Carrying Amount of Liabilities	2,001	2,085
Credit card loan securitizations
Variable Interest Entity [Line Items]
Maximum Exposure to Loss	0	0
Credit card loan securitizations | Consolidated
Variable Interest Entity [Line Items]
Carrying Amount of Assets	24,393	25,474
Carrying Amount of Liabilities	14,692	14,692
Credit card loan securitizations | Unconsolidated
Variable Interest Entity [Line Items]
Carrying Amount of Assets	0	0
Carrying Amount of Liabilities	0	0
Auto loan securitizations
Variable Interest Entity [Line Items]
Maximum Exposure to Loss	0	0
Auto loan securitizations | Consolidated
Variable Interest Entity [Line Items]
Carrying Amount of Assets	4,491	5,019
Carrying Amount of Liabilities	3,655	4,021
Auto loan securitizations | Unconsolidated
Variable Interest Entity [Line Items]
Carrying Amount of Assets	0	0
Carrying Amount of Liabilities	0	0
Total securitization-related VIEs
Variable Interest Entity [Line Items]
Maximum Exposure to Loss	0	0
Total securitization-related VIEs | Consolidated
Variable Interest Entity [Line Items]
Carrying Amount of Assets	28,884	30,493
Carrying Amount of Liabilities	18,347	18,713
Total securitization-related VIEs | Unconsolidated
Variable Interest Entity [Line Items]
Carrying Amount of Assets	0	0
Carrying Amount of Liabilities	$ 0	$ 0