Fair Value Measurement - Level 3 Inputs (Details) $ in Millions	Jun. 30, 2024 USD ($) $ / shares $ / bbl $ / MMBTU	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans	$ 38,250		$ 38,851
MSRs	8,847	$ 8,605	8,522	$ 8,229	$ 7,755	$ 7,973
Equity securities for which quoted prices are not readily available	$ 3,564		4,500	$ 4,673
Assumed par value for price input (in dollars per share) | $ / shares	$ 100
Level 3 | Yield | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.05
Level 3 | Yield | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.20
Level 3 | Yield | Discounted cash flows | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.11
Level 3 | Loss severity | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0
Level 3 | Loss severity | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	1
Level 3 | Loss severity | Discounted cash flows | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.50
Level 3 | Interest rate volatility | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.0007
Level 3 | Interest rate volatility | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.0490
Level 3 | Interest rate volatility | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.0115
Level 3 | Bermudan switch value | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0
Level 3 | Bermudan switch value | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.50
Level 3 | Bermudan switch value | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.18
Level 3 | Interest rate correlation | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	(0.82)
Level 3 | Interest rate correlation | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.97
Level 3 | Interest rate correlation | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.64
Level 3 | IR-FX correlation | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	(0.35)
Level 3 | IR-FX correlation | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.60
Level 3 | IR-FX correlation | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.06
Level 3 | Credit correlation | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.26
Level 3 | Credit correlation | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.68
Level 3 | Credit correlation | Discounted cash flows | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.47
Level 3 | Credit spread | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.0001
Level 3 | Credit spread | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.2500
Level 3 | Credit spread | Discounted cash flows | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.0068
Level 3 | Recovery rate | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.20
Level 3 | Recovery rate | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.75
Level 3 | Recovery rate | Discounted cash flows | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.35
Level 3 | Equity volatility | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.01
Level 3 | Equity volatility | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	1.34
Level 3 | Equity volatility | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.26
Level 3 | Equity correlation | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	(0.10)
Level 3 | Equity correlation | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	1
Level 3 | Equity correlation | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.56
Level 3 | Equity-FX correlation | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	(0.88)
Level 3 | Equity-FX correlation | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.65
Level 3 | Equity-FX correlation | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	(0.32)
Level 3 | Equity-IR correlation | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	(0.15)
Level 3 | Equity-IR correlation | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.15
Level 3 | Equity-IR correlation | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits, measurement inputs	0.05
Level 3 | Residential mortgage-backed securities and loans | Yield | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans, measurement input	0
Level 3 | Residential mortgage-backed securities and loans | Yield | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans, measurement input	0.88
Level 3 | Residential mortgage-backed securities and loans | Yield | Discounted cash flows | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans, measurement input	0.08
Level 3 | Residential mortgage-backed securities and loans | Prepayment speed | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans, measurement input	0.03
Level 3 | Residential mortgage-backed securities and loans | Prepayment speed | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans, measurement input	0.12
Level 3 | Residential mortgage-backed securities and loans | Prepayment speed | Discounted cash flows | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans, measurement input	0.09
Level 3 | Residential mortgage-backed securities and loans | Conditional default rate | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans, measurement input	0
Level 3 | Residential mortgage-backed securities and loans | Conditional default rate | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans, measurement input	0.07
Level 3 | Residential mortgage-backed securities and loans | Conditional default rate | Discounted cash flows | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans, measurement input	0
Level 3 | Residential mortgage-backed securities and loans | Loss severity | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans, measurement input	0
Level 3 | Residential mortgage-backed securities and loans | Loss severity | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans, measurement input	1.10
Level 3 | Residential mortgage-backed securities and loans | Loss severity | Discounted cash flows | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans, measurement input	0.02
Level 3 | Commercial mortgage-backed securities and loans | Price (in USD/share) | Market comparables | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans, measurement input | $ / shares	0
Level 3 | Commercial mortgage-backed securities and loans | Price (in USD/share) | Market comparables | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans, measurement input | $ / shares	90
Level 3 | Commercial mortgage-backed securities and loans | Price (in USD/share) | Market comparables | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans, measurement input | $ / shares	82
Level 3 | Corporate debt securities | Price (in USD/share) | Market comparables | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities, trading, measurement input | $ / shares	0
Level 3 | Corporate debt securities | Price (in USD/share) | Market comparables | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities, trading, measurement input | $ / shares	175
Level 3 | Corporate debt securities | Price (in USD/share) | Market comparables | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities, trading, measurement input | $ / shares	93
Level 3 | Loans | Price (in USD/share) | Market comparables | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans, measurement input | $ / shares	0
Level 3 | Loans | Price (in USD/share) | Market comparables | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans, measurement input | $ / shares	107
Level 3 | Loans | Price (in USD/share) | Market comparables | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans, measurement input | $ / shares	78
Level 3 | Non-U.S. government debt | Price (in USD/share) | Market comparables | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities, trading, measurement input | $ / shares	0
Level 3 | Non-U.S. government debt | Price (in USD/share) | Market comparables | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities, trading, measurement input | $ / shares	100
Level 3 | Non-U.S. government debt | Price (in USD/share) | Market comparables | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities, trading, measurement input | $ / shares	93
Level 3 | Net interest rate derivatives | Prepayment speed | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0
Level 3 | Net interest rate derivatives | Prepayment speed | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.20
Level 3 | Net interest rate derivatives | Prepayment speed | Discounted cash flows | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.05
Level 3 | Net interest rate derivatives | Interest rate volatility | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.0007
Level 3 | Net interest rate derivatives | Interest rate volatility | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.0490
Level 3 | Net interest rate derivatives | Interest rate volatility | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.0115
Level 3 | Net interest rate derivatives | Interest rate spread volatility | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.0037
Level 3 | Net interest rate derivatives | Interest rate spread volatility | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.0077
Level 3 | Net interest rate derivatives | Interest rate spread volatility | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.0064
Level 3 | Net interest rate derivatives | Bermudan switch value | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0
Level 3 | Net interest rate derivatives | Bermudan switch value | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.50
Level 3 | Net interest rate derivatives | Bermudan switch value | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.18
Level 3 | Net interest rate derivatives | Interest rate correlation | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	(0.82)
Level 3 | Net interest rate derivatives | Interest rate correlation | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.97
Level 3 | Net interest rate derivatives | Interest rate correlation | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.64
Level 3 | Net interest rate derivatives | IR-FX correlation | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	(0.35)
Level 3 | Net interest rate derivatives | IR-FX correlation | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.60
Level 3 | Net interest rate derivatives | IR-FX correlation | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.06
Level 3 | Net credit derivatives | Price (in USD/share) | Market comparables | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs | $ / shares	0
Level 3 | Net credit derivatives | Price (in USD/share) | Market comparables | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs | $ / shares	115
Level 3 | Net credit derivatives | Price (in USD/share) | Market comparables | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs | $ / shares	72
Level 3 | Net credit derivatives | Credit correlation | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.26
Level 3 | Net credit derivatives | Credit correlation | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.68
Level 3 | Net credit derivatives | Credit correlation | Discounted cash flows | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.47
Level 3 | Net credit derivatives | Credit spread | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0
Level 3 | Net credit derivatives | Credit spread | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.2999
Level 3 | Net credit derivatives | Credit spread | Discounted cash flows | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.0352
Level 3 | Net credit derivatives | Recovery rate | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.10
Level 3 | Net credit derivatives | Recovery rate | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.90
Level 3 | Net credit derivatives | Recovery rate | Discounted cash flows | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.58
Level 3 | Net foreign exchange derivatives | Prepayment speed | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.11
Level 3 | Net foreign exchange derivatives | Prepayment speed | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.11
Level 3 | Net foreign exchange derivatives | Prepayment speed | Discounted cash flows | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.11
Level 3 | Net foreign exchange derivatives | IR-FX correlation | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	(0.40)
Level 3 | Net foreign exchange derivatives | IR-FX correlation | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.60
Level 3 | Net foreign exchange derivatives | IR-FX correlation | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.24
Level 3 | Net foreign exchange derivatives | Interest rate curve | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.02
Level 3 | Net foreign exchange derivatives | Interest rate curve | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.14
Level 3 | Net foreign exchange derivatives | Interest rate curve | Discounted cash flows | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.06
Level 3 | Net equity derivatives | Forward equity price | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.78
Level 3 | Net equity derivatives | Forward equity price | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	1.53
Level 3 | Net equity derivatives | Forward equity price | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	1.02
Level 3 | Net equity derivatives | Equity volatility | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.05
Level 3 | Net equity derivatives | Equity volatility | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	1.47
Level 3 | Net equity derivatives | Equity volatility | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.31
Level 3 | Net equity derivatives | Equity correlation | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	(0.10)
Level 3 | Net equity derivatives | Equity correlation | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	1
Level 3 | Net equity derivatives | Equity correlation | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.56
Level 3 | Net equity derivatives | Equity-FX correlation | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	(0.88)
Level 3 | Net equity derivatives | Equity-FX correlation | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.65
Level 3 | Net equity derivatives | Equity-FX correlation | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	(0.32)
Level 3 | Net equity derivatives | Equity-IR correlation | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	(0.15)
Level 3 | Net equity derivatives | Equity-IR correlation | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.15
Level 3 | Net equity derivatives | Equity-IR correlation | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.05
Level 3 | Net commodity derivatives | Oil commodity forward (in USD/ BBL) | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs | $ / bbl	89
Level 3 | Net commodity derivatives | Oil commodity forward (in USD/ BBL) | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs | $ / bbl	270
Level 3 | Net commodity derivatives | Oil commodity forward (in USD/ BBL) | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs | $ / bbl	179
Level 3 | Net commodity derivatives | Natural gas commodity forward (in USD/ MMBTU) | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs | $ / MMBTU	1
Level 3 | Net commodity derivatives | Natural gas commodity forward (in USD/ MMBTU) | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs | $ / MMBTU	6
Level 3 | Net commodity derivatives | Natural gas commodity forward (in USD/ MMBTU) | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs | $ / MMBTU	4
Level 3 | Net commodity derivatives | Commodity volatility | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.02
Level 3 | Net commodity derivatives | Commodity volatility | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.24
Level 3 | Net commodity derivatives | Commodity volatility | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.05
Level 3 | Net commodity derivatives | Commodity correlation | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	(0.35)
Level 3 | Net commodity derivatives | Commodity correlation | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.98
Level 3 | Net commodity derivatives | Commodity correlation | Option pricing | Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	0.32
Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans	$ 38,250		38,851
MSRs	8,847		8,522
Long-term debt, short-term borrowings, and deposits	772,029		541,419
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans	2,993		3,079
MSRs	8,847		8,522
Long-term debt, short-term borrowings, and deposits	48,133		$ 42,182
Other level 3 asset and liabilities, net	1,349
Equity securities for which quoted prices are not readily available	776
Recurring | Level 3 | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
MSRs	8,847
Long-term debt, short-term borrowings, and deposits	1,251
Recurring | Level 3 | Option pricing
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term debt, short-term borrowings, and deposits	34,684
Recurring | Level 3 | Residential mortgage-backed securities and loans | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans	1,523
Recurring | Level 3 | Commercial mortgage-backed securities and loans | Market comparables
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans	1,539
Recurring | Level 3 | Corporate debt securities | Market comparables
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities, trading	408
Recurring | Level 3 | Loans | Market comparables
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans	1,346
Recurring | Level 3 | Trading loans | Market comparables
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans	626
Recurring | Level 3 | Trading loans | Market comparables | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans	65
Recurring | Level 3 | Non-trading loans | Discounted cash flows | Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans	810
Recurring | Level 3 | Non-trading loans | Market comparables
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans	720
Recurring | Level 3 | Non-trading loans | Market comparables | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans	1,500
Recurring | Level 3 | Non-U.S. government debt | Market comparables
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities, trading	193
Recurring | Level 3 | Net interest rate derivatives | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	(1)
Recurring | Level 3 | Net interest rate derivatives | Option pricing
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	1,302
Recurring | Level 3 | Net credit derivatives | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	149
Recurring | Level 3 | Net credit derivatives | Market comparables
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	31
Recurring | Level 3 | Net foreign exchange derivatives | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	(55)
Recurring | Level 3 | Net foreign exchange derivatives | Option pricing
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	223
Recurring | Level 3 | Net equity derivatives | Option pricing
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	(2,991)
Recurring | Level 3 | Net commodity derivatives | Option pricing
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	(472)
Recurring | Level 3 | Mortgage-backed securities, U.S. GSEs and government agencies | Discounted cash flows | Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans	708
Recurring | Level 3 | Residential mortgage-backed securities | Discounted cash flows | Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans	5
Recurring | Level 3 | Commercial mortgage-backed securities | Market comparables | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans	11
Recurring | Level 3 | Other assets
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Equity securities for which quoted prices are not readily available	$ 654