Fair Value Measurement - Level 3 Inputs (Details) $ / shares in Units, $ in Millions	Dec. 31, 2016 USD ($) $ / shares $ / bbl	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	$ (2,360)	$ (1,749)	$ (2,061)	$ 326
Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Liability fair value	207,289	191,103
Level 3 Analysis - Supplemental Data:
Trading assets	308,000	284,101
Trading liabilities	136,659	126,897
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Liability fair value	25,402	25,528
Level 3 Analysis - Supplemental Data:
Trading assets	7,894	11,930
Trading liabilities	8,196	9,758
Interest rate
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	$ 1,263	876	626	2,379
Interest rate | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Interest rate correlation	(30.00%)
Interest rate spread volatility	3.00%
Interest rate | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Interest rate correlation	100.00%
Interest rate spread volatility	38.00%
Interest rate | Option pricing | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	$ 1,263
Credit
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	$ 98	549	189	95
Credit | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Credit correlation	30.00%
Credit | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Credit correlation	85.00%
Credit | Discounted cash flows | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	$ 98
Foreign exchange
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	$ (1,384)	(725)	(526)	(1,200)
Foreign exchange | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Foreign exchange correlation	(30.00%)
Foreign exchange | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Foreign exchange correlation	65.00%
Foreign exchange | Option pricing | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	$ (1,384)
Equity
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	$ (2,252)	(1,514)	(1,785)	(1,063)
Equity | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Equity volatility	20.00%
Equity | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Equity volatility	60.00%
Equity | Option pricing | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	$ (2,252)
Commodity
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	$ (85)	$ (935)	$ (565)	$ 115
Commodity | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Forward commodity price | $ / bbl	46
Commodity | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Forward commodity price | $ / bbl	59
Commodity | Discounted cash flows | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	$ (85)
Long-term debt, other borrowed funds, and deposits | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Credit correlation	30.00%
Long-term debt, other borrowed funds, and deposits | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Credit correlation	85.00%
Long-term debt, other borrowed funds, and deposits | Discounted cash flows | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Liability fair value	$ 476
Long-term debt, other borrowed funds, and deposits | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Interest rate correlation	(30.00%)
Interest rate spread volatility	3.00%
Foreign exchange correlation	(30.00%)
Equity correlation	(50.00%)
Long-term debt, other borrowed funds, and deposits | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Interest rate correlation	100.00%
Interest rate spread volatility	38.00%
Foreign exchange correlation	65.00%
Equity correlation	80.00%
Long-term debt, other borrowed funds, and deposits | Option pricing | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Liability fair value	$ 16,669
Credit derivatives with underlying mortgage risk | Recurring | Level 3
Level 3 Analysis - Supplemental Data:
Trading liabilities	226
Credit derivatives with underlying asset-backed securities risk | Recurring | Level 3
Level 3 Analysis - Supplemental Data:
Trading liabilities	$ 333
Residential mortgage-backed securities and loans | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Yield	4.00%
Prepayment speed	0.00%
Conditional default rate	0.00%
Loss severity	0.00%
Residential mortgage-backed securities and loans | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Yield	18.00%
Prepayment speed	20.00%
Conditional default rate	34.00%
Loss severity	90.00%
Residential mortgage-backed securities and loans | Discounted cash flows | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Yield	5.00%
Prepayment speed	8.00%
Conditional default rate	15.00%
Loss severity	37.00%
Residential mortgage-backed securities and loans | Discounted cash flows | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset fair value	$ 2,861
Commercial mortgage-backed securities and loans | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Yield	1.00%
Conditional default rate	0.00%
Loss severity	40.00%
Commercial mortgage-backed securities and loans | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Yield	32.00%
Conditional default rate	100.00%
Loss severity	40.00%
Commercial mortgage-backed securities and loans | Discounted cash flows | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Yield	8.00%
Conditional default rate	69.00%
Loss severity	40.00%
Commercial mortgage-backed securities and loans | Discounted cash flows | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset fair value	$ 1,555
Corporate debt securities, obligations of U.S. states and municipalities, and other | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Yield	1.00%
Credit spread	0.40%
Corporate debt securities, obligations of U.S. states and municipalities, and other | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Yield	17.00%
Credit spread	3.75%
Corporate debt securities, obligations of U.S. states and municipalities, and other | Discounted cash flows | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Yield	9.00%
Credit spread	0.96%
Corporate debt securities, obligations of U.S. states and municipalities, and other | Discounted cash flows | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset fair value	$ 764
Corporate debt securities, obligations of U.S. states and municipalities, and other | Market comparables | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Price (in dollars per share) | $ / shares	$ 0
Corporate debt securities, obligations of U.S. states and municipalities, and other | Market comparables | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Price (in dollars per share) | $ / shares	121
Corporate debt securities, obligations of U.S. states and municipalities, and other | Market comparables | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Price (in dollars per share) | $ / shares	$ 91
Corporate debt securities, obligations of U.S. states and municipalities, and other | Market comparables | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset fair value	$ 3,744
Collateralized loan obligations | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Prepayment speed	20.00%
Conditional default rate	2.00%
Loss severity	30.00%
Credit spread	3.03%
Collateralized loan obligations | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Prepayment speed	20.00%
Conditional default rate	2.00%
Loss severity	30.00%
Credit spread	4.75%
Collateralized loan obligations | Discounted cash flows | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Prepayment speed	20.00%
Conditional default rate	2.00%
Loss severity	30.00%
Credit spread	3.39%
Collateralized loan obligations | Discounted cash flows | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset fair value	$ 663
Collateralized loan obligations | Market comparables | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Price (in dollars per share) | $ / shares	$ 0
Collateralized loan obligations | Market comparables | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Price (in dollars per share) | $ / shares	111
Collateralized loan obligations | Market comparables | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Price (in dollars per share) | $ / shares	$ 73
Collateralized loan obligations | Market comparables | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset fair value	$ 158
Mortgage servicing rights | Discounted cash flows | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset fair value	$ 6,096
Private equity investments | Market comparables | Private equity investments | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
EBITDA multiple	6.4
Private equity investments | Market comparables | Private equity investments | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
EBITDA multiple	11.5
Private equity investments | Market comparables | Private equity investments | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
EBITDA multiple	7.9
Private equity investments | Market comparables | Recurring | Level 3 | Private equity investments
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset fair value	$ 1,606
Credit derivatives with underlying mortgage risk | Recurring | Level 3
Level 3 Analysis - Supplemental Data:
Trading assets	394
Credit derivatives with underlying asset-backed securities risk | Recurring | Level 3
Level 3 Analysis - Supplemental Data:
Trading assets	$ 362