Fair Value Measurement - Level 3 Inputs (Details)	Jun. 30, 2015 USD ($) $ / bbl	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	$ (746,000,000)	$ (1,848,000,000)	$ (2,061,000,000)	$ (1,855,000,000)	$ (66,000,000)	$ 326,000,000
Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	$ 859,000,000	650,000,000	626,000,000	1,533,000,000	2,090,000,000	2,379,000,000
Interest rate contracts | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Interest rate correlation	(54.00%)
Interest rate spread volatility	4.00%
Interest rate contracts | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Interest rate correlation	99.00%
Interest rate spread volatility	26.00%
Credit derivatives
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	$ 432,000,000	275,000,000	189,000,000	134,000,000	244,000,000	95,000,000
Credit derivatives | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Credit correlation	40.00%
Credit derivatives | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Credit correlation	90.00%
Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	$ 405,000,000	707,000,000	(526,000,000)	(1,194,000,000)	(1,282,000,000)	(1,200,000,000)
Foreign exchange contracts | Option pricing | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Foreign exchange correlation	0.00%
Foreign exchange contracts | Option pricing | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Foreign exchange correlation	60.00%
Equity
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	$ (1,848,000,000)	(2,745,000,000)	(1,785,000,000)	(2,206,000,000)	(1,060,000,000)	(1,063,000,000)
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	65.00%
Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	$ (594,000,000)	$ (735,000,000)	(565,000,000)	$ (122,000,000)	$ (58,000,000)	$ 115,000,000
Commodity contracts | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Forward commodity price | $ / bbl	50
Commodity contracts | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Forward commodity price | $ / bbl	90
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	40.00%
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	90.00%
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	(54.00%)
Interest rate spread volatility	4.00%
Foreign exchange correlation	0.00%
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	99.00%
Interest rate spread volatility	26.00%
Foreign exchange correlation	60.00%
Equity correlation	80.00%
Residential mortgage-backed securities and loans | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Discount rate	3.00%
Prepayment rate	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]
Discount rate	45.00%
Prepayment rate	16.00%
Conditional default rate	100.00%
Loss severity	100.00%
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]
Discount rate	6.00%
Prepayment rate	6.00%
Conditional default rate	13.00%
Loss severity	28.00%
Commercial mortgage-backed securities and loans | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Discount rate	1.00%
Conditional default rate	0.00%
Commercial mortgage-backed securities and loans | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Discount rate	25.00%
Conditional default rate	94.00%
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]
Discount rate	4.00%
Conditional default rate	8.00%
Loss severity	40.00%
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]
Discount rate	1.00%
Credit spread	0.60%
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]
Discount rate	18.00%
Credit spread	2.70%
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]
Discount rate	5.00%
Credit spread	2.31%
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	$ 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	129
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	$ 92
Asset-backed securities, Collateralized loan obligations | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Prepayment rate	20.00%
Conditional default rate	2.00%
Loss severity	40.00%
Asset-backed securities, Collateralized loan obligations | Discounted cash flows | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Credit spread	2.89%
Asset-backed securities, Collateralized loan obligations | Discounted cash flows | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Credit spread	3.99%
Asset-backed securities, Collateralized loan obligations | Discounted cash flows | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Prepayment rate	20.00%
Conditional default rate	2.00%
Loss severity	40.00%
Credit spread	3.05%
Asset-backed securities, Collateralized loan obligations | Market comparables | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Price	$ 0
Asset-backed securities, Collateralized loan obligations | Market comparables | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Price	99
Asset-backed securities, Collateralized loan obligations | Market comparables | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Price	$ 70
Private equity | Private equity direct investments | Market comparables | Minimum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Liquidity adjustment	0.00%
EBITDA multiple	6.7
Private equity | Private equity direct investments | Market comparables | Maximum
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Liquidity adjustment	17.00%
EBITDA multiple	9.9
Private equity | Private equity direct investments | Market comparables | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Liquidity adjustment	8.00%
EBITDA multiple	8.3
Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Liability fair value	$ 201,149,000,000		211,754,000,000
Level 3 Analysis - Supplemental Data:
Trading Securities	310,351,000,000		319,889,000,000
Trading liabilities	139,422,000,000		152,815,000,000
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Liability fair value	30,487,000,000		32,059,000,000
Level 3 Analysis - Supplemental Data:
Trading Securities	15,941,000,000		22,489,000,000
Trading liabilities	11,946,000,000		$ 14,698,000,000
Recurring | Level 3 | Interest rate contracts | Option pricing
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	859,000,000
Recurring | Level 3 | Credit derivatives | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	432,000,000
Recurring | Level 3 | Foreign exchange contracts | Option pricing
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	405,000,000
Recurring | Level 3 | Equity | Option pricing
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	(1,848,000,000)
Recurring | Level 3 | Commodity contracts | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative asset (liability)	(594,000,000)
Recurring | Level 3 | Long-term debt, other borrowed funds, and deposits | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Liability fair value	1,717,000,000
Recurring | Level 3 | Long-term debt, other borrowed funds, and deposits | Option pricing
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Liability fair value	15,661,000,000
Recurring | Level 3 | Credit derivatives with underlying mortgage risk
Level 3 Analysis - Supplemental Data:
Trading liabilities	396,000,000
Recurring | Level 3 | Credit derivatives with underlying asset-backed securities risk
Level 3 Analysis - Supplemental Data:
Trading liabilities	569,000,000
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]
Asset fair value	6,287,000,000
Recurring | Level 3 | Commercial mortgage-backed securities and loans | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset fair value	4,136,000,000
Recurring | Level 3 | Corporate debt securities, obligations of U.S. states and municipalities, and other | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset fair value	3,956,000,000
Recurring | Level 3 | Corporate debt securities, obligations of U.S. states and municipalities, and other | Market comparables
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset fair value	4,652,000,000
Recurring | Level 3 | Asset-backed securities, Collateralized loan obligations | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset fair value	772,000,000
Recurring | Level 3 | Asset-backed securities, Collateralized loan obligations | Market comparables
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset fair value	146,000,000
Recurring | Level 3 | Mortgage servicing rights | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset fair value	7,571,000,000
Recurring | Level 3 | Private equity | Private equity direct investments | Market comparables
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset fair value	1,987,000,000
Recurring | Level 3 | Credit derivatives with underlying mortgage risk
Level 3 Analysis - Supplemental Data:
Trading Securities	450,000,000
Recurring | Level 3 | Credit derivatives with underlying asset-backed securities risk
Level 3 Analysis - Supplemental Data:
Trading Securities	$ 617,000,000