Fair Value, Assets and Liabilities, Valuation Techniques - Nonrecurring Basis (Details) - Nonrecurring [Member] $ in Millions	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Loans held for sale	$ 855	$ 623
Total assets after derivative netting	7,555	9,234
Nonmarketable equity securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Nonmarketable equity securities	2,440	4,440
Fair value, inputs, level 3 [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Loans held for sale	258	297
Total insignificant level 3 assets	2	58
Total assets after derivative netting	1,734	2,709
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	$ 258	$ 297
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	0.001
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	0.879	0.958
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	0.186	0.175
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	0.034	0.030
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	0.144	0.132
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	0.061	0.058
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	0.036	0.054
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	0.572	0.586
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	0.162	0.166
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	0.021	0.021
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	0.296	0.338
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	0.123	0.118
Fair value, inputs, level 3 [Member] | Nonmarketable equity securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Nonmarketable equity securities	$ 1,474	$ 2,354
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		$ 42
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		0.050
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		0.050
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		0.050
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	$ 1,015	$ 1,721
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	0.9	0.7
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	9.3	27.1
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	2.4	8.4
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	$ 459	$ 591
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	(1.000)	(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	(0.058)	(0.115)
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	(0.370)	(0.429)