Fair Value (Fair Value Measurements - Recurring Quantitative Information) (Details) $ in Millions	Sep. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities – available for sale	$ 60,338	$ 41,785
Fair value	3,503	3,686
Financial derivatives - Swaps related to sales of certain Visa Class B common shares	(2,360)	(3,538)
Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities – available for sale	60,338	41,785
Loans, fair value	1,173	1,238
Equity investments	3,242	2,717
Financial derivatives - Swaps related to sales of certain Visa Class B common shares	(4,627)	(5,899)
Recurring assets - fair value	75,841	56,862
Recurring liabilities - fair value	6,356	6,953
Residential mortgage-backed non-agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities – available for sale	628	696
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	2,063	1,952
Financial derivatives - Swaps related to sales of certain Visa Class B common shares	(276)	(145)
Insignificant assets, net of liabilities fair value disclosure	58	22
Total recurring assets net of recurring liabilities - fair value	6,760	7,050
Level 3 | Total consumer | Residential real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, fair value	70	75
Level 3 | Total consumer | Loans - Residential real estate - Uninsured
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, fair value	518	546
Level 3 | Total consumer | Home equity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, fair value	80	87
Level 3 | Total consumer | Loans - Home equity - First-lien
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, fair value	16	18
Level 3 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities – available for sale	881	956
Loans, fair value	684	726
Equity investments	2,063	1,952
Financial derivatives - Swaps related to sales of certain Visa Class B common shares	(281)	(152)
Recurring assets - fair value	7,225	7,448
Recurring liabilities - fair value	465	398
Level 3 | Commercial mortgage loans held for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale, fair value	4	11
Level 3 | Residential mortgage-backed non-agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities – available for sale	628	696
Level 3 | Asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities – available for sale	96	102
Level 3 | Residential mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	2,528	2,654
Level 3 | Commercial mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	$ 975	$ 1,032
Spread over the benchmark curve | Level 3 | Commercial mortgage loans held for sale | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.0570	0.0575
Spread over the benchmark curve | Level 3 | Commercial mortgage loans held for sale | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.1085	0.3610
Spread over the benchmark curve | Level 3 | Commercial mortgage loans held for sale | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.0980	0.1647
Spread over the benchmark curve | Level 3 | Residential mortgage-backed non-agency securities | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.0247	0.0285
Spread over the benchmark curve | Level 3 | Asset-backed | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.0193	0.0248
Spread over the benchmark curve | Level 3 | Residential mortgage servicing rights | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.0221	0.0337
Spread over the benchmark curve | Level 3 | Residential mortgage servicing rights | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.1732	0.1668
Spread over the benchmark curve | Level 3 | Residential mortgage servicing rights | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.0755	0.0765
Constant prepayment rate | Level 3 | Residential mortgage-backed non-agency securities | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.010	0.010
Constant prepayment rate | Level 3 | Residential mortgage-backed non-agency securities | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.279	0.279
Constant prepayment rate | Level 3 | Residential mortgage-backed non-agency securities | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.042	0.037
Constant prepayment rate | Level 3 | Asset-backed | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.010	0.010
Constant prepayment rate | Level 3 | Asset-backed | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.080	0.280
Constant prepayment rate | Level 3 | Asset-backed | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.038	0.051
Constant prepayment rate | Level 3 | Residential mortgage servicing rights | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.000	0.000
Constant prepayment rate | Level 3 | Residential mortgage servicing rights | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.516	0.336
Constant prepayment rate | Level 3 | Residential mortgage servicing rights | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.072	0.064
Constant prepayment rate | Level 3 | Commercial mortgage servicing rights | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.043	0.053
Constant prepayment rate | Level 3 | Commercial mortgage servicing rights | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.091	0.097
Constant prepayment rate | Level 3 | Commercial mortgage servicing rights | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.044	0.055
Constant default rate | Level 3 | Residential mortgage-backed non-agency securities | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.000	0.000
Constant default rate | Level 3 | Residential mortgage-backed non-agency securities | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.120	0.120
Constant default rate | Level 3 | Residential mortgage-backed non-agency securities | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.019	0.027
Constant default rate | Level 3 | Asset-backed | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.000	0.000
Constant default rate | Level 3 | Asset-backed | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.070	0.043
Constant default rate | Level 3 | Asset-backed | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.015	0.017
Loss severity | Level 3 | Minimum | Total consumer | Loans - Residential real estate - Uninsured
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.000	0.000
Loss severity | Level 3 | Minimum | Total consumer | Loans - Home equity - First-lien
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.000	0.000
Loss severity | Level 3 | Maximum | Total consumer | Loans - Residential real estate - Uninsured
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	1.000	1.000
Loss severity | Level 3 | Maximum | Total consumer | Loans - Home equity - First-lien
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	1.000	1.000
Loss severity | Level 3 | Weighted Average | Total consumer | Residential real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.060	0.060
Loss severity | Level 3 | Weighted Average | Total consumer | Loans - Residential real estate - Uninsured
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.051	0.054
Loss severity | Level 3 | Weighted Average | Total consumer | Loans - Home equity - First-lien
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.123	0.144
Loss severity | Level 3 | Residential mortgage-backed non-agency securities | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.150	0.100
Loss severity | Level 3 | Residential mortgage-backed non-agency securities | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.774	0.690
Loss severity | Level 3 | Residential mortgage-backed non-agency securities | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.432	0.412
Loss severity | Level 3 | Asset-backed | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.350	0.200
Loss severity | Level 3 | Asset-backed | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	1.000	1.000
Loss severity | Level 3 | Asset-backed | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.468	0.495
Cumulative default rate | Level 3 | Minimum | Total consumer | Loans - Residential real estate - Uninsured
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.036	0.036
Cumulative default rate | Level 3 | Minimum | Total consumer | Loans - Home equity - First-lien
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.036	0.036
Cumulative default rate | Level 3 | Maximum | Total consumer | Loans - Residential real estate - Uninsured
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	1.000	1.000
Cumulative default rate | Level 3 | Maximum | Total consumer | Loans - Home equity - First-lien
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	1.000	1.000
Cumulative default rate | Level 3 | Weighted Average | Total consumer | Loans - Residential real estate - Uninsured
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.572	0.591
Cumulative default rate | Level 3 | Weighted Average | Total consumer | Loans - Home equity - First-lien
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.569	0.609
Discount rate | Level 3 | Minimum | Total consumer | Loans - Residential real estate - Uninsured
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.055	0.055
Discount rate | Level 3 | Minimum | Total consumer | Loans - Home equity - First-lien
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.055	0.055
Discount rate | Level 3 | Maximum | Total consumer | Loans - Residential real estate - Uninsured
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.075	0.075
Discount rate | Level 3 | Maximum | Total consumer | Loans - Home equity - First-lien
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.075	0.075
Discount rate | Level 3 | Weighted Average | Total consumer | Residential real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.068	0.078
Discount rate | Level 3 | Weighted Average | Total consumer | Loans - Residential real estate - Uninsured
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.058	0.058
Discount rate | Level 3 | Weighted Average | Total consumer | Loans - Home equity - First-lien
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.061	0.062
Discount rate | Level 3 | Commercial mortgage servicing rights | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.090	0.076
Discount rate | Level 3 | Commercial mortgage servicing rights | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.109	0.100
Discount rate | Level 3 | Commercial mortgage servicing rights | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.107	0.096
Credit and liquidity discount | Level 3 | Minimum | Total consumer | Home equity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.003	0.003
Credit and liquidity discount | Level 3 | Maximum | Total consumer | Home equity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	1.000	1.000
Credit and liquidity discount | Level 3 | Weighted Average | Total consumer | Home equity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing receivable, measurement input	0.410	0.438
Multiple of earnings | Level 3 | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, measurement input	0.055	0.045
Multiple of earnings | Level 3 | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, measurement input	0.270	0.267
Multiple of earnings | Level 3 | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, measurement input	0.103	0.101
Estimated Conversion Factor | Level 3 | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	1.54	1.59
Estimated Annual Growth Rate | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	0.160	0.160