Fair Value, Assets and Liabilities, Valuation Techniques - Nonrecurring Basis (Details) - Nonrecurring [Member] $ in Millions	Mar. 31, 2022 USD ($) $ / loan	Dec. 31, 2021 USD ($) $ / loan
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Loans held for sale	$ 4,547	$ 5,318
Other assets	1,848	1,548
Total assets at fair value on a nonrecurring basis	9,214	15,316
Nonmarketable equity securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Nonmarketable equity securities	2,323	7,027
Fair value, inputs, level 3 [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Loans held for sale	1,422	1,407
Other assets	102	175
Total insignificant level 3 assets	3
Total assets at fair value on a nonrecurring basis	2,647	2,914
Fair value, inputs, level 3 [Member] | Valuation technique, discounted cash flow [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Loans held for sale	1,422	1,407
Other assets		175
Fair value, inputs, level 3 [Member] | Valuation, market comparable pricing [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Other assets	102
Fair value, inputs, level 3 [Member] | Commercial [Member] | Valuation technique, discounted cash flow [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Mortgage servicing rights	75	567
Fair value, inputs, level 3 [Member] | Residential [Member] | Non-government insured/guaranteed [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Loans held for sale	200	200
Fair value, inputs, level 3 [Member] | Residential [Member] | Government insured or guaranteed [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Loans held for sale	$ 1,200	$ 1,200
Fair value, inputs, level 3 [Member] | Measurement input, default rate [Member] | Valuation technique, discounted cash flow [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Loans held for sale, measurement input	0.002	0.002
Fair value, inputs, level 3 [Member] | Measurement input, default rate [Member] | Valuation technique, discounted cash flow [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Loans held for sale, measurement input	0.830	0.783
Fair value, inputs, level 3 [Member] | Measurement input, default rate [Member] | Valuation technique, discounted cash flow [Member] | Weighted average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Loans held for sale, measurement input	0.231	0.256
Fair value, inputs, level 3 [Member] | Measurement input, discount rate [Member] | Valuation technique, discounted cash flow [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Loans held for sale, measurement input	0.006	0.006
Other assets, measurement input		0.002
Fair value, inputs, level 3 [Member] | Measurement input, discount rate [Member] | Valuation technique, discounted cash flow [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Loans held for sale, measurement input	0.127	0.120
Other assets, measurement input		0.044
Fair value, inputs, level 3 [Member] | Measurement input, discount rate [Member] | Valuation technique, discounted cash flow [Member] | Weighted average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Loans held for sale, measurement input	0.036	0.033
Other assets, measurement input		0.029
Fair value, inputs, level 3 [Member] | Measurement input, discount rate [Member] | Commercial [Member] | Valuation technique, discounted cash flow [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Mortgage servicing rights, measurement input	0.052	0.040
Fair value, inputs, level 3 [Member] | Measurement input, discount rate [Member] | Commercial [Member] | Valuation technique, discounted cash flow [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Mortgage servicing rights, measurement input	0.052	0.045
Fair value, inputs, level 3 [Member] | Measurement input, discount rate [Member] | Commercial [Member] | Valuation technique, discounted cash flow [Member] | Weighted average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Mortgage servicing rights, measurement input	0.052	0.040
Fair value, inputs, level 3 [Member] | Measurement input, loss severity [Member] | Valuation technique, discounted cash flow [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Loans held for sale, measurement input	0.003	0.004
Fair value, inputs, level 3 [Member] | Measurement input, loss severity [Member] | Valuation technique, discounted cash flow [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Loans held for sale, measurement input	0.429	0.456
Fair value, inputs, level 3 [Member] | Measurement input, loss severity [Member] | Valuation technique, discounted cash flow [Member] | Weighted average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Loans held for sale, measurement input	0.041	0.048
Fair value, inputs, level 3 [Member] | Measurement input, prepayment rate [Member] | Valuation technique, discounted cash flow [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Loans held for sale, measurement input	0.041	0.054
Fair value, inputs, level 3 [Member] | Measurement input, prepayment rate [Member] | Valuation technique, discounted cash flow [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Loans held for sale, measurement input	1.000	1.000
Fair value, inputs, level 3 [Member] | Measurement input, prepayment rate [Member] | Valuation technique, discounted cash flow [Member] | Weighted average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Loans held for sale, measurement input	0.363	0.389
Fair value, inputs, level 3 [Member] | Measurement input, prepayment rate [Member] | Commercial [Member] | Valuation technique, discounted cash flow [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Mortgage servicing rights, measurement input	0.000	0.000
Fair value, inputs, level 3 [Member] | Measurement input, prepayment rate [Member] | Commercial [Member] | Valuation technique, discounted cash flow [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Mortgage servicing rights, measurement input	0.206	0.206
Fair value, inputs, level 3 [Member] | Measurement input, prepayment rate [Member] | Commercial [Member] | Valuation technique, discounted cash flow [Member] | Weighted average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Mortgage servicing rights, measurement input	0.067	0.055
Fair value, inputs, level 3 [Member] | Measurement input, cost to service per loan [Member] | Commercial [Member] | Valuation technique, discounted cash flow [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Mortgage servicing rights, measurement input | $ / loan	3,775	150
Fair value, inputs, level 3 [Member] | Measurement input, cost to service per loan [Member] | Commercial [Member] | Valuation technique, discounted cash flow [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Mortgage servicing rights, measurement input | $ / loan	3,775	3,381
Fair value, inputs, level 3 [Member] | Measurement input, cost to service per loan [Member] | Commercial [Member] | Valuation technique, discounted cash flow [Member] | Weighted average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Mortgage servicing rights, measurement input | $ / loan	3,775	2,771
Fair value, inputs, level 3 [Member] | Measurement input, multiples [Member] | Valuation, market comparable pricing [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Other assets, measurement input	8.0
Fair value, inputs, level 3 [Member] | Measurement input, multiples [Member] | Valuation, market comparable pricing [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Other assets, measurement input	8.0
Fair value, inputs, level 3 [Member] | Measurement input, multiples [Member] | Valuation, market comparable pricing [Member] | Weighted average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Other assets, measurement input	8.0
Fair value, inputs, level 3 [Member] | Nonmarketable equity securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Nonmarketable equity securities	$ 1,048	$ 765
Fair value, inputs, level 3 [Member] | Nonmarketable equity securities [Member] | Valuation technique, discounted cash flow [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Nonmarketable equity securities		$ 5
Fair value, inputs, level 3 [Member] | Nonmarketable equity securities [Member] | Measurement input, discount rate [Member] | Valuation technique, discounted cash flow [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Nonmarketable equity securities, measurement input		0.105
Fair value, inputs, level 3 [Member] | Nonmarketable equity securities [Member] | Measurement input, discount rate [Member] | Valuation technique, discounted cash flow [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Nonmarketable equity securities, measurement input		0.105
Fair value, inputs, level 3 [Member] | Nonmarketable equity securities [Member] | Measurement input, discount rate [Member] | Valuation technique, discounted cash flow [Member] | Weighted average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Nonmarketable equity securities, measurement input		0.105
Fair value, inputs, level 3 [Member] | Nonmarketable equity securities [Member] | Measurement input, multiples [Member] | Valuation, market comparable pricing [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Nonmarketable equity securities	$ 129	$ 15
Fair value, inputs, level 3 [Member] | Nonmarketable equity securities [Member] | Measurement input, multiples [Member] | Valuation, market comparable pricing [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Nonmarketable equity securities, measurement input	1.1	2.0
Fair value, inputs, level 3 [Member] | Nonmarketable equity securities [Member] | Measurement input, multiples [Member] | Valuation, market comparable pricing [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Nonmarketable equity securities, measurement input	4.0	3.3
Fair value, inputs, level 3 [Member] | Nonmarketable equity securities [Member] | Measurement input, multiples [Member] | Valuation, market comparable pricing [Member] | Weighted average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Nonmarketable equity securities, measurement input	2.6	2.8
Fair value, inputs, level 3 [Member] | Nonmarketable equity securities [Member] | Measurement input, market comparability adjustment [Member] | Valuation, market comparable pricing [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Nonmarketable equity securities	$ 916	$ 745
Fair value, inputs, level 3 [Member] | Nonmarketable equity securities [Member] | Measurement input, market comparability adjustment [Member] | Valuation, market comparable pricing [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Nonmarketable equity securities, measurement input	(0.820)	(1.000)
Fair value, inputs, level 3 [Member] | Nonmarketable equity securities [Member] | Measurement input, market comparability adjustment [Member] | Valuation, market comparable pricing [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Nonmarketable equity securities, measurement input	(0.080)	(0.330)
Fair value, inputs, level 3 [Member] | Nonmarketable equity securities [Member] | Measurement input, market comparability adjustment [Member] | Valuation, market comparable pricing [Member] | Weighted average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Nonmarketable equity securities, measurement input	(0.210)	(0.590)