Fair Value Measurements - Quantitative Information about Recurring Fair Value Measurement of Assets and Liabilities Classified as Level 3 (Detail) $ in Millions		Mar. 31, 2024 USD ($) $ / shares	Dec. 31, 2023 USD ($)
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Fair Value	[1]	$ 25,550	$ 25,696
Long-term debt	[1]	(19,439)	(18,661)
Level 3
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Commercial loans held-for-sale		25	32
Mortgage servicing rights		19	19
Domestic deposits		(331)	(293)
Long-term debt		0	0
Structured notes | Level 3
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Long-term debt		(1,959)	(1,919)
Asset-backed securities | Level 3
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Fair Value		102	104
Interest rate contracts | Level 3
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivative assets (liability		(3)	(4)
Foreign exchange contracts | Level 3
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivative assets (liability		0	0
Equity contracts | Level 3
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivative assets (liability		67	21
Credit contracts | Level 3
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivative assets (liability			1
Other Contracts | Level 3
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivative assets (liability		$ (30)	$ (35)
Probability to fund for rate lock commitments | Interest rate contracts | Recurring | Minimum | Market comparable adjusted for probability to fund and, where applicable, option pricing model
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives		0.51	0.71
Probability to fund for rate lock commitments | Interest rate contracts | Recurring | Maximum | Market comparable adjusted for probability to fund and, where applicable, option pricing model
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives		1	0.92
Probability to fund for rate lock commitments | Interest rate contracts | Recurring | Weighted Average | Market comparable adjusted for probability to fund and, where applicable, option pricing model
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives		0.84	0.84
Interest rate yield curve | Interest rate contracts | Recurring | Market comparable adjusted for probability to fund and, where applicable, option pricing model
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives		0.09	0.09
Cross-currency basis | Foreign exchange contracts | Recurring | Option pricing model
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives		(0.0018)	0.0008
Equity / Equity Index volatility | Recurring | Minimum | Option adjusted discounted cash flows
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Domestic deposits		0.06	0.07
Equity / Equity Index volatility | Recurring | Minimum | Option adjusted discounted cash flows | Structured notes
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Long-term debt		0.07	0.07
Equity / Equity Index volatility | Recurring | Maximum | Option adjusted discounted cash flows
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Domestic deposits		0.29	0.29
Equity / Equity Index volatility | Recurring | Maximum | Option adjusted discounted cash flows | Structured notes
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Long-term debt		0.95	0.95
Equity / Equity Index volatility | Recurring | Weighted Average | Option adjusted discounted cash flows
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Domestic deposits		0.13	0.13
Equity / Equity Index volatility | Recurring | Weighted Average | Option adjusted discounted cash flows | Structured notes
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Long-term debt		0.23	0.22
Equity / Equity Index volatility | Equity contracts | Recurring | Minimum | Option pricing model
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives		0.06	0.06
Equity / Equity Index volatility | Equity contracts | Recurring | Maximum | Option pricing model
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives		1.30	1.11
Equity / Equity Index volatility | Equity contracts | Recurring | Weighted Average | Option pricing model
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives		0.40	0.41
Equity / Equity and Equity / Index correlation | Recurring | Minimum | Option adjusted discounted cash flows
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Domestic deposits		0.43	0.51
Equity / Equity and Equity / Index correlation | Recurring | Minimum | Option adjusted discounted cash flows | Structured notes
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Long-term debt		0.35	0.45
Equity / Equity and Equity / Index correlation | Recurring | Maximum | Option adjusted discounted cash flows
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Domestic deposits		0.88	0.93
Equity / Equity and Equity / Index correlation | Recurring | Maximum | Option adjusted discounted cash flows | Structured notes
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Long-term debt		0.97	0.97
Equity / Equity and Equity / Index correlation | Recurring | Weighted Average | Option adjusted discounted cash flows
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Domestic deposits		0.66	0.71
Equity / Equity and Equity / Index correlation | Recurring | Weighted Average | Option adjusted discounted cash flows | Structured notes
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Long-term debt		0.84	0.84
Equity / Equity and Equity / Index correlation | Equity contracts | Recurring | Minimum | Option pricing model
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives		0.35	0.45
Equity / Equity and Equity / Index correlation | Equity contracts | Recurring | Maximum | Option pricing model
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives		0.97	0.97
Equity / Equity and Equity / Index correlation | Equity contracts | Recurring | Weighted Average | Option pricing model
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives		0.82	0.84
Equity forward price | Equity contracts | Recurring | Minimum | Option pricing model
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives | $ / shares		42
Equity forward price | Equity contracts | Recurring | Maximum | Option pricing model
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives | $ / shares		6,897
Equity forward price | Equity contracts | Recurring | Weighted Average | Option pricing model
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives | $ / shares		1,798
Equity forward price | Equity contracts | Recurring | Minimum | Option pricing model
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives			41
Equity forward price | Equity contracts | Recurring | Maximum | Option pricing model
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives			6,245
Equity forward price | Equity contracts | Recurring | Weighted Average | Option pricing model
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives			643
Credit default swap spreads | Recurring | Option adjusted discounted cash flows | Structured notes
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Long-term debt		0.0795	0.0948
Credit default swap spreads | Credit contracts | Recurring | Minimum | Option pricing model
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives			0.0059
Credit default swap spreads | Credit contracts | Recurring | Maximum | Option pricing model
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives			0.1558
Credit default swap spreads | Credit contracts | Recurring | Weighted Average | Option pricing model
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives			0.0160
Conversion rate | Other Contracts | Recurring | Discounted cash flows
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives		1.6	1.6
Expected duration | Other Contracts | Recurring | Discounted cash flows
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Derivatives		0.8	1
Market assumptions related to yields for comparable instruments | Recurring | Minimum | Market comparables and internal assumptions
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Loans Held-for-sale, Measurement Input		0.48	0.78
Market assumptions related to yields for comparable instruments | Recurring | Maximum | Market comparables and internal assumptions
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Loans Held-for-sale, Measurement Input		1.01	1
Market assumptions related to yields for comparable instruments | Recurring | Weighted Average | Market comparables and internal assumptions
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Loans Held-for-sale, Measurement Input		0.91	0.90
Market assumptions related to yields for comparable instruments | Asset-backed securities | Recurring | Minimum | Discounted cash flows
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Available for sale securities		0.02	0.02
Market assumptions related to yields for comparable instruments | Asset-backed securities | Recurring | Maximum | Discounted cash flows
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Available for sale securities		0.03	0.03
Market assumptions related to yields for comparable instruments | Asset-backed securities | Recurring | Weighted Average | Discounted cash flows
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Available for sale securities		0.02	0.02
Constant prepayment rates | Recurring | Minimum | Discounted cash flows
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Mortgage servicing rights		0.06	0.06
Constant prepayment rates | Recurring | Maximum | Discounted cash flows
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Mortgage servicing rights		0.16	0.17
Constant prepayment rates | Recurring | Weighted Average | Discounted cash flows
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Mortgage servicing rights		0.06	0.06
Discount rate | Recurring | Minimum | Discounted cash flows
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Mortgage servicing rights		0.10	0.10
Discount rate | Recurring | Maximum | Discounted cash flows
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Mortgage servicing rights		0.14	0.14
Discount rate | Recurring | Weighted Average | Discounted cash flows
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Mortgage servicing rights		0.10	0.10
Estimated annualized costs to service | Recurring | Minimum | Discounted cash flows
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Mortgage servicing rights		72	72
Estimated annualized costs to service | Recurring | Maximum | Discounted cash flows
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Mortgage servicing rights		75	77
Estimated annualized costs to service | Recurring | Weighted Average | Discounted cash flows
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Mortgage servicing rights		74	74

[1] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") at March 31, 2024 and December 31, 2023. Assets and liabilities exclude intercompany balances that eliminate in consolidation. See Note 15, "Variable Interest Entities," for additional information. March 31, 2024December 31, 2023(in millions)AssetsOther assets$21 $23 Total assets$21 $23 LiabilitiesInterest, taxes and other liabilities$28 $17 Total liabilities$28 $17