Fair Value Measurement - Level 3 Inputs (Details) $ in Millions	Jun. 30, 2019 USD ($) $ / shares $ / bbl	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans	$ 4,309		$ 3,151
MSRs	$ 5,093	$ 5,957	6,130	$ 6,241	$ 6,202	$ 6,030
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]
Other assets, measurement inputs	0.08
Level 3 | Yield | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Other assets, measurement inputs	0.12
Level 3 | Yield | Discounted cash flows | Weighted average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Other assets, measurement inputs	0.12
Level 3 | Price (in dollars per share) | Market comparables | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Other assets, measurement inputs | $ / shares	19
Level 3 | Price (in dollars per share) | Market comparables | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Other assets, measurement inputs | $ / shares	113
Level 3 | Price (in dollars per share) | Market comparables | Weighted average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Other assets, measurement inputs | $ / shares	34
Level 3 | Interest rate spread 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	0.0020
Level 3 | Interest rate spread 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	0.0030
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	(0.28)
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	0.96
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	(0.45)
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 | Credit spread | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Other assets, measurement inputs	0.0045
Level 3 | Credit spread | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Other assets, measurement inputs	0.0045
Level 3 | Credit spread | Discounted cash flows | Weighted average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Other assets, measurement inputs	0.0045
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	0.25
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	0.98
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	(0.75)
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	0.59
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	0.20
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	0.60
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	0.15
Level 3 | Residential mortgage-backed securities and loans | Yield | Discounted cash flows | Weighted average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans, measurement input	0.06
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
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	0.26
Level 3 | Residential mortgage-backed securities and loans | Prepayment speed | Discounted cash flows | Weighted average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans, measurement input	0.13
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	0.05
Level 3 | Residential mortgage-backed securities and loans | Conditional default rate | Discounted cash flows | Weighted average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans, measurement input	0.01
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	0.70
Level 3 | Residential mortgage-backed securities and loans | Loss severity | Discounted cash flows | Weighted average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans, measurement input	0.01
Level 3 | Commercial mortgage-backed securities and loans | Price (in dollars per 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 dollars per 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	110
Level 3 | Commercial mortgage-backed securities and loans | Price (in dollars per share) | Market comparables | Weighted average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans, measurement input | $ / shares	85
Level 3 | Obligations of U.S. states and municipalities | Price (in dollars per share) | Market comparables | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities, trading, measurement input | $ / shares	66
Level 3 | Obligations of U.S. states and municipalities | Price (in dollars per 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 | Obligations of U.S. states and municipalities | Price (in dollars per share) | Market comparables | Weighted average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities, trading, measurement input | $ / shares	97
Level 3 | Corporate debt securities | Price (in dollars per 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 dollars per share) | Market comparables | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities, trading, measurement input | $ / shares	109
Level 3 | Corporate debt securities | Price (in dollars per share) | Market comparables | Weighted average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities, trading, measurement input | $ / shares	83
Level 3 | Loans | Yield | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans, measurement input	0.05
Level 3 | Loans | Yield | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans, measurement input	0.18
Level 3 | Loans | Yield | Discounted cash flows | Weighted average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans, measurement input	0.07
Level 3 | Loans | Price (in dollars per share) | Market comparables | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans, measurement input | $ / shares	2
Level 3 | Loans | Price (in dollars per share) | Market comparables | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans, measurement input | $ / shares	102
Level 3 | Loans | Price (in dollars per share) | Market comparables | Weighted average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans, measurement input | $ / shares	80
Level 3 | Asset-backed securities | Price (in dollars per share) | Market comparables | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities, trading, measurement input | $ / shares	1
Level 3 | Asset-backed securities | Price (in dollars per 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 | Asset-backed securities | Price (in dollars per share) | Market comparables | Weighted average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities, trading, measurement input | $ / shares	38
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	0.04
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	0.30
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	0.0020
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	0.0030
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	(0.28)
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	0.96
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	0.45
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 credit derivatives | Conditional default 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	0.02
Level 3 | Net credit derivatives | Conditional default 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	0.91
Level 3 | Net credit derivatives | Loss severity | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	1
Level 3 | Net credit derivatives | Loss severity | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	1.00
Level 3 | Net credit derivatives | Price (in dollars per share) | Market comparables | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	1
Level 3 | Net credit derivatives | Price (in dollars per share) | Market comparables | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs	115
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	0.35
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	0.60
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	0.0006
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	0.1402
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	0.20
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	0.70
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	0.09
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	0.09
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	(0.45)
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 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	0.14
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	0.60
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	0.25
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	0.98
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	(0.75)
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	0.59
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	0.20
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	0.60
Level 3 | Net commodity derivatives | Forward commodity price | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs | $ / bbl	49
Level 3 | Net commodity derivatives | Forward commodity price | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability), measurement inputs | $ / bbl	70
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	0.05
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	0.65
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	(0.48)
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	0.95
Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans	$ 4,309		3,151
MSRs	5,093		6,130
Long-term debt, short-term borrowings, and deposits	259,981		234,238
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans	5		122
MSRs	5,093		6,130
Long-term debt, short-term borrowings, and deposits	38,770		$ 34,784
Other level 3 asset and liabilities, net	200
Recurring | Level 3 | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
MSRs	5,093
Other assets	358
Recurring | Level 3 | Market comparables
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Other assets	814
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	27,981
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	942
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	218
Recurring | Level 3 | Obligations of U.S. states and municipalities | Market comparables
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities, trading	680
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	562
Recurring | Level 3 | Loans | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans	212
Recurring | Level 3 | 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	283
Recurring | Level 3 | Loans | Market comparables
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans	1,079
Recurring | Level 3 | Loans | Market comparables | Commercial
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans	204
Recurring | Level 3 | Asset-backed securities | Market comparables
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities, trading	33
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)	72
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)	(616)
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)	(265)
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)	33
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)	(170)
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)	(23)
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)	(2,560)
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)	(908)
Recurring | Level 3 | Mortgage-backed securities, U.S. 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	617
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	42
Recurring | Level 3 | Commercial | Market comparables | Commercial
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans	9
Recurring | Level 3 | Nontrading loans | Market comparables | Commercial
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans	$ 5