Fair Value (Fair Value Measurements - Recurring Quantitative Information) (Details) - Fair Value, Recurring $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring assets - fair value	$ 69,243	$ 147,484
Financial and nonfinancial liabilities, fair value disclosure	(9,502)	(4,518)
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring assets - fair value	6,546	5,882
Financial and nonfinancial liabilities, fair value disclosure	(398)	(463)
Total recurring assets net of recurring liabilities - fair value	6,148	5,419
Level 3 | Loans held for sale | Commercial mortgage loans held for sale | Discounted Cash Flow, Spread Over the Benchmark Curve
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring assets - fair value	$ 38	$ 49
Level 3 | Loans held for sale | Commercial mortgage loans held for sale | Discounted Cash Flow, Spread Over the Benchmark Curve | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Spread over the benchmark curve	5.65%	5.55%
Level 3 | Loans held for sale | Commercial mortgage loans held for sale | Discounted Cash Flow, Spread Over the Benchmark Curve | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Spread over the benchmark curve	48.50%	159.90%
Level 3 | Loans held for sale | Commercial mortgage loans held for sale | Discounted Cash Flow, Spread Over the Benchmark Curve | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Spread over the benchmark curve	35.53%	99.96%
Level 3 | Securities available for sale | Residential mortgage-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring assets - fair value	$ 925	$ 1,097
Level 3 | Securities available for sale | Residential mortgage-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Spread over the benchmark curve	2.22%	1.63%
Level 3 | Securities available for sale | Asset-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring assets - fair value	$ 138	$ 163
Level 3 | Securities available for sale | Asset-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Spread over the benchmark curve	2.65%	1.82%
Level 3 | Loans - Residential real estate | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring assets - fair value	$ 78	$ 109
Level 3 | Loans - Residential real estate | Consensus Pricing
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring assets - fair value	$ 589	$ 622
Level 3 | Loans - Residential real estate | Consensus Pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cumulative default rate	3.60%	3.60%
Level 3 | Loans - Residential real estate | Consensus Pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cumulative default rate	100.00%	100.00%
Level 3 | Loans - Residential real estate | Consensus Pricing | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cumulative default rate	69.80%	74.20%
Level 3 | Loans - Home equity | Consensus Pricing
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring assets - fair value	$ 27	$ 28
Level 3 | Loans - Home equity | Consensus Pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cumulative default rate	3.60%	3.60%
Level 3 | Loans - Home equity | Consensus Pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cumulative default rate	100.00%	100.00%
Level 3 | Loans - Home equity | Consensus Pricing | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cumulative default rate	74.80%	75.80%
Level 3 | Loans - Home equity | Consensus Pricing
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring assets - fair value	$ 110	$ 125
Level 3 | Equity investments | Multiple of adjusted earnings
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring assets - fair value	$ 1,867	$ 1,680
Level 3 | Equity investments | Multiple of adjusted earnings | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Multiple of earnings	0.050	0.050
Level 3 | Equity investments | Multiple of adjusted earnings | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Multiple of earnings	0.168	0.144
Level 3 | Equity investments | Multiple of adjusted earnings | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Multiple of earnings	0.092	0.088
Level 3 | Mortgage Servicing Rights | Commercial mortgage loans held for sale | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring assets - fair value	$ 988	$ 740
Level 3 | Mortgage Servicing Rights | Residential mortgage loans held for sale | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring assets - fair value	$ 1,620	$ 1,078
Level 3 | Mortgage Servicing Rights | Residential mortgage loans held for sale | Discounted cash flow | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Spread over the benchmark curve	2.68%	2.49%
Level 3 | Mortgage Servicing Rights | Residential mortgage loans held for sale | Discounted cash flow | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Spread over the benchmark curve	17.29%	22.18%
Level 3 | Mortgage Servicing Rights | Residential mortgage loans held for sale | Discounted cash flow | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Spread over the benchmark curve	8.18%	8.57%
Level 3 | Financial derivatives | Visa Class B Swap | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial and nonfinancial liabilities, fair value disclosure	$ (197)	$ (277)
Estimated growth rate of Visa Class A share price	16.00%	16.00%
Level 3 | Financial derivatives | Visa Class B Swap | Discounted cash flow | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated conversion factor of Class B shares into Class A shares	160.60%	161.80%
Level 3 | Insignificant Assets, Net of Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring assets - fair value		$ 5
Financial and nonfinancial liabilities, fair value disclosure	$ (35)
Measurement Input, Constant Prepayment Rate | Level 3 | Securities available for sale | Residential mortgage-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.010	0.010
Measurement Input, Constant Prepayment Rate | Level 3 | Securities available for sale | Residential mortgage-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.307	0.307
Measurement Input, Constant Prepayment Rate | Level 3 | Securities available for sale | Residential mortgage-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.102	0.113
Measurement Input, Constant Prepayment Rate | Level 3 | Securities available for sale | Asset-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.010	0.010
Measurement Input, Constant Prepayment Rate | Level 3 | Securities available for sale | Asset-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.400	0.400
Measurement Input, Constant Prepayment Rate | Level 3 | Securities available for sale | Asset-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.111	0.111
Measurement Input, Constant Prepayment Rate | Level 3 | Mortgage Servicing Rights | Commercial mortgage loans held for sale | Discounted cash flow | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.043	0.050
Measurement Input, Constant Prepayment Rate | Level 3 | Mortgage Servicing Rights | Commercial mortgage loans held for sale | Discounted cash flow | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.111	0.155
Measurement Input, Constant Prepayment Rate | Level 3 | Mortgage Servicing Rights | Commercial mortgage loans held for sale | Discounted cash flow | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.049	0.055
Measurement Input, Constant Prepayment Rate | Level 3 | Mortgage Servicing Rights | Residential mortgage loans held for sale | Discounted cash flow | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.000	0.000
Measurement Input, Constant Prepayment Rate | Level 3 | Mortgage Servicing Rights | Residential mortgage loans held for sale | Discounted cash flow | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.445	0.410
Measurement Input, Constant Prepayment Rate | Level 3 | Mortgage Servicing Rights | Residential mortgage loans held for sale | Discounted cash flow | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.081	0.126
Measurement Input, Constant Default Rate | Level 3 | Securities available for sale | Residential mortgage-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.000	0.000
Measurement Input, Constant Default Rate | Level 3 | Securities available for sale | Residential mortgage-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.130	0.169
Measurement Input, Constant Default Rate | Level 3 | Securities available for sale | Residential mortgage-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.041	0.046
Measurement Input, Constant Default Rate | Level 3 | Securities available for sale | Asset-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.007	0.014
Measurement Input, Constant Default Rate | Level 3 | Securities available for sale | Asset-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.073	0.200
Measurement Input, Constant Default Rate | Level 3 | Securities available for sale | Asset-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.025	0.032
Measurement Input, Loss Severity | Level 3 | Securities available for sale | Residential mortgage-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.150	0.200
Measurement Input, Loss Severity | Level 3 | Securities available for sale | Residential mortgage-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.964	0.964
Measurement Input, Loss Severity | Level 3 | Securities available for sale | Residential mortgage-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.462	0.476
Measurement Input, Loss Severity | Level 3 | Securities available for sale | Asset-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.150	0.080
Measurement Input, Loss Severity | Level 3 | Securities available for sale | Asset-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	1.000	1.000
Measurement Input, Loss Severity | Level 3 | Securities available for sale | Asset-backed | Priced By A Third Party Vendor Using Discounted Cash Flow Pricing Model | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, measurement input	0.489	0.574
Measurement Input, Loss Severity | Level 3 | Loans - Residential real estate | Discounted cash flow | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, measurement input	0.060	0.060
Measurement Input, Loss Severity | Level 3 | Loans - Residential real estate | Consensus Pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, measurement input	0.000	0.000
Measurement Input, Loss Severity | Level 3 | Loans - Residential real estate | Consensus Pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, measurement input	1.000	1.000
Measurement Input, Loss Severity | Level 3 | Loans - Residential real estate | Consensus Pricing | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, measurement input	0.059	0.069
Measurement Input, Loss Severity | Level 3 | Loans - Home equity | Consensus Pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, measurement input	0.000	0.000
Measurement Input, Loss Severity | Level 3 | Loans - Home equity | Consensus Pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, measurement input	1.000	0.984
Measurement Input, Loss Severity | Level 3 | Loans - Home equity | Consensus Pricing | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, measurement input	0.189	0.177
Measurement Input, Discount Rate | Level 3 | Loans - Residential real estate | Discounted cash flow | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, measurement input	0.061	0.035
Measurement Input, Discount Rate | Level 3 | Loans - Residential real estate | Consensus Pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, measurement input	0.049	0.048
Measurement Input, Discount Rate | Level 3 | Loans - Residential real estate | Consensus Pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, measurement input	0.069	0.068
Measurement Input, Discount Rate | Level 3 | Loans - Residential real estate | Consensus Pricing | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, measurement input	0.053	0.052
Measurement Input, Discount Rate | Level 3 | Loans - Home equity | Consensus Pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, measurement input	0.049	0.048
Measurement Input, Discount Rate | Level 3 | Loans - Home equity | Consensus Pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, measurement input	0.069	0.068
Measurement Input, Discount Rate | Level 3 | Loans - Home equity | Consensus Pricing | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, measurement input	0.059	0.060
Measurement Input, Discount Rate | Level 3 | Mortgage Servicing Rights | Commercial mortgage loans held for sale | Discounted cash flow | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.069	0.054
Measurement Input, Discount Rate | Level 3 | Mortgage Servicing Rights | Commercial mortgage loans held for sale | Discounted cash flow | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.092	0.080
Measurement Input, Discount Rate | Level 3 | Mortgage Servicing Rights | Commercial mortgage loans held for sale | Discounted cash flow | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing asset, measurement input	0.089	0.078
Credit And Liquidity Discount | Level 3 | Loans - Home equity | Consensus Pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Credit and liquidity discount	0.40%	0.50%
Credit And Liquidity Discount | Level 3 | Loans - Home equity | Consensus Pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Credit and liquidity discount	100.00%	100.00%
Credit And Liquidity Discount | Level 3 | Loans - Home equity | Consensus Pricing | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Credit and liquidity discount	45.50%	47.30%