Fair Value Measurement - Level 3 Inputs (Details) $ in Millions	Mar. 31, 2019 USD ($) $ / shares $ / bbl	Dec. 31, 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	$ 3,719	$ 3,151
MSRs	$ 5,957	6,130	$ 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	0.10
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	0.09
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	110
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	0.0016
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	0.0038
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	(0.25)
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 | 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	(0.50)
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	0.0055
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	0.0055
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	0.0055
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	0.18
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	0.07
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	0.22
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	0.11
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	1
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	0.03
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	102
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	87
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	63
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	98
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	111
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	82
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	0.06
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	0.08
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	0
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	105
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	65
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	0.0016
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	0.0038
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	(0.25)
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 | 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	0.01
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	0.93
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 | 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	0.30
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	0.55
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	0.1396
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 | 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	(0.50)
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	0.65
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	52
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	69
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	0.57
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	(0.51)
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	$ 3,719	3,151
MSRs	5,957	6,130
Long-term debt, short-term borrowings, and deposits	261,411	234,238
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans	123	122
MSRs	5,957	6,130
Long-term debt, short-term borrowings, and deposits	37,035	$ 34,784
Other level 3 asset and liabilities, net	305
Recurring | Level 3 | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
MSRs	5,957
Other assets	214
Recurring | Level 3 | Market comparables
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Other assets	930
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	27,685
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	748
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	397
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	623
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	568
Recurring | Level 3 | Loans | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans	226
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	255
Recurring | Level 3 | Loans | Market comparables
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans	1,007
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	253
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	119
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)	70
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)	(217)
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)	(162)
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)	47
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)	(158)
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)	(198)
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)	(2,066)
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)	(665)
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	408
Recurring | Level 3 | Mortgage-backed securities, U.S. government agencies | Market comparables | Commercial
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt securities and loans	4
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	85
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	17
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	$ 123