FAIR VALUE MEASUREMENT (Details 4) (Level 3, USD $)	3 Months Ended
	Mar. 31, 2012 correlation
Interest-bearing deposits
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of liabilities as of the balance sheet date	458,000,000
Interest-bearing deposits | Internal Model | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
IR-FX Correlation	(0.3890)
IR-IR Correlation	0.2000
IR Volatility (as a percent)	13.00%
Interest-bearing deposits | Internal Model | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
IR-FX Correlation	0.5539
IR-IR Correlation	0.9000
IR Volatility (as a percent)	20.00%
Federal funds purchased and securities loaned or sold under agreements to repurchase
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of liabilities as of the balance sheet date	1,025,000,000
Federal funds purchased and securities loaned or sold under agreements to repurchase | Cash flow | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Interest Rate (as a percent)	0.93%
Federal funds purchased and securities loaned or sold under agreements to repurchase | Cash flow | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Interest Rate (as a percent)	2.83%
Short-term borrowings and long-term debt
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of liabilities as of the balance sheet date	6,941,000,000
Short-term borrowings and long-term debt | Price-based | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Interest Rate (as a percent)	0.25%
Price	0.01
IR Volatility (as a percent)	8.70%
Equity Volatility	8.10%
Equity Forward	23.60%
Equity-Equity Correlation	0.2620
Equity-FX Correlation	(0.8300)
Short-term borrowings and long-term debt | Price-based | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Interest Rate (as a percent)	2.00%
Price	128.53
IR Volatility (as a percent)	71.63%
Equity Volatility	241.80%
Equity Forward	248.00%
Equity-Equity Correlation	0.9800
Equity-FX Correlation	0.6000
Short-term borrowings and long-term debt | Internal Model | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Credit Spread (as a percent)	0.70%
Short-term borrowings and long-term debt | Internal Model | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Credit Spread (as a percent)	0.10399%
Federal funds sold and securities borrowed or purchased under agreements to resell
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of assets as of the balance sheet date	4,497,000,000
Federal funds sold and securities borrowed or purchased under agreements to resell | Cash flow | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Interest Rate (as a percent)	1.52%
Federal funds sold and securities borrowed or purchased under agreements to resell | Cash flow | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Interest Rate (as a percent)	2.15%
Trading and investment securities
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of assets as of the balance sheet date	32,062,000,000
Derivatives
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of assets as of the balance sheet date	26,861,000,000
Loans and leases
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of assets as of the balance sheet date	4,279,000,000
Loans and leases | Cash flow | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Credit Spread (as a percent)	0.46%
Loans and leases | Cash flow | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Credit Spread (as a percent)	6.68%
Loans and leases | Price-based | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Price	0.01
Recovery Rate (as a percent)	36.00%
Loans and leases | Price-based | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Price	113.38
Recovery Rate (as a percent)	70.00%
Loans and leases | Internal Model | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	0.90%
Loans and leases | Internal Model | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	3.50%
Mortgage servicing rights
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of assets as of the balance sheet date	2,691,000,000
Mortgage servicing rights | Cash flow | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	0.00%
Prepayment period	0.78
Mortgage servicing rights | Cash flow | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	44.83%
Prepayment period	10.59
Interest rate contracts | Derivatives, assets
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of assets as of the balance sheet date	3,533,000,000
Interest rate contracts | Derivatives, assets | Cash flow | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	1.50%
Interest rate contracts | Derivatives, assets | Cash flow | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	15.00%
Interest rate contracts | Derivatives, assets | Internal Model | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Interest Rate (as a percent)	0.23%
IR-FX Correlation	(0.5000)
IR-IR Correlation	(0.1328)
IR Volatility (as a percent)	8.70%
Interest rate contracts | Derivatives, assets | Internal Model | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Interest Rate (as a percent)	3.25%
IR-FX Correlation	0.6000
IR-IR Correlation	1.0000
IR Volatility (as a percent)	85.00%
Foreign exchange contracts | Derivatives, assets
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of assets as of the balance sheet date	1,489,000,000
Foreign exchange contracts | Derivatives, assets | Internal Model | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Recovery Rate (as a percent)	20.00%
FX Volatility (as a percent)	0.06%
IR-FX Correlation	0.4000
IR Volatility (as a percent)	8.70%
FX-Credit Correlation	0.6500
Foreign exchange contracts | Derivatives, assets | Internal Model | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Recovery Rate (as a percent)	40.00%
FX Volatility (as a percent)	29.00%
IR-FX Correlation	0.6000
IR Volatility (as a percent)	71.63%
FX-Credit Correlation	1.0000
Equity contracts | Derivatives, assets
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of assets as of the balance sheet date	4,559,000,000
Equity contracts | Derivatives, assets | Cash flow | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	1.50%
Equity contracts | Derivatives, assets | Cash flow | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	15.00%
Equity contracts | Derivatives, assets | Price-based | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Price	0.01
FX Volatility (as a percent)	14.84%
Equity Volatility	3.36%
Equity Forward	23.60%
Equity-Equity Correlation	0.2620
Yield Volatility	4.45%
Equity-IR Correlation	(0.4300)
Equity contracts | Derivatives, assets | Price-based | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Price	115.00
FX Volatility (as a percent)	16.04%
Equity Volatility	241.80%
Equity Forward	248.00%
Equity-Equity Correlation	0.9800
Yield Volatility	13.00%
Equity-IR Correlation	0.5700
Equity contracts | Derivatives, assets | Internal Model | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Credit Spread (as a percent)	1.50%
Equity contracts | Derivatives, assets | Internal Model | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Credit Spread (as a percent)	5.00%
Commodity contracts | Derivatives, assets
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of assets as of the balance sheet date	2,723,000,000
Commodity contracts | Derivatives, assets | Internal Model | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Commodity Correlation	(0.7200)
Commodity Volatility (as a percent)	8.00%
Forward Price	0.7400
Commodity contracts | Derivatives, assets | Internal Model | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Commodity Correlation	0.9600
Commodity Volatility (as a percent)	141.00%
Forward Price	3.2800
Credit derivatives | Derivatives, assets
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of assets as of the balance sheet date	12,232,000,000
Credit derivatives | Derivatives, assets | Cash flow | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Credit Spread (as a percent)	0.01%
Credit derivatives | Derivatives, assets | Cash flow | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Credit Spread (as a percent)	0.33555%
Credit derivatives | Derivatives, assets | Price-based | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Price	0.00
Recovery Rate (as a percent)	9.00%
FX-Credit Correlation	0.6500
Credit derivatives | Derivatives, assets | Price-based | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Price	100.00
Recovery Rate (as a percent)	75.00%
FX-Credit Correlation	1.0000
Credit derivatives | Derivatives, assets | Internal Model | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Credit Correlation	0.0500
Credit derivatives | Derivatives, assets | Internal Model | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Credit Correlation	0.9500
Nontrading derivatives and other financial assets and liabilities measured on a recurring basis (gross) | Derivatives
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of assets as of the balance sheet date	2,325,000,000
Nontrading derivatives and other financial assets and liabilities measured on a recurring basis (gross) | Derivatives | Price-based | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Price	100.00
Nontrading derivatives and other financial assets and liabilities measured on a recurring basis (gross) | Derivatives | Price-based | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Price	100.00
Nontrading derivatives and other financial assets and liabilities measured on a recurring basis (gross) | Derivatives | Internal Model | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Redemption Rate (as a percent)	6.70%
Nontrading derivatives and other financial assets and liabilities measured on a recurring basis (gross) | Derivatives | Internal Model | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Redemption Rate (as a percent)	99.60%
Mortgage-backed securities | Trading and investment securities
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of assets as of the balance sheet date	3,950,000,000
Mortgage-backed securities | Trading and investment securities | Cash flow | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	0.01%
Mortgage-backed securities | Trading and investment securities | Cash flow | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	35.95%
Mortgage-backed securities | Trading and investment securities | Price-based | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Prepayment period	0.78
Mortgage-backed securities | Trading and investment securities | Price-based | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Prepayment period	10.59
Price	125.43
State and municipal | Trading and investment securities
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of assets as of the balance sheet date	905,000,000
State and municipal | Trading and investment securities | Cash flow | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	0.01%
State and municipal | Trading and investment securities | Cash flow | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	6.00%
State and municipal | Trading and investment securities | Price-based | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Underlying price(s)	100.00
State and municipal | Trading and investment securities | Price-based | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Underlying price(s)	100.00
Foreign government | Trading and investment securities
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of assets as of the balance sheet date	1,208,000,000
Foreign government | Trading and investment securities | Cash flow | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Interest Rate (as a percent)	0.07%
Foreign government | Trading and investment securities | Cash flow | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Interest Rate (as a percent)	9.10%
Foreign government | Trading and investment securities | Price-based | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Price	0.001
Foreign government | Trading and investment securities | Price-based | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Price	115.00
Foreign government | Trading and investment securities | Internal Model | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	1.00%
Foreign government | Trading and investment securities | Internal Model | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	16.00%
Corporate | Trading and investment securities
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of assets as of the balance sheet date	4,825,000,000
Corporate | Trading and investment securities | Cash flow | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Credit Spread (as a percent)	0.22%
Corporate | Trading and investment securities | Cash flow | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Credit Spread (as a percent)	1.10%
Corporate | Trading and investment securities | Price-based | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	1.50%
Corporate | Trading and investment securities | Price-based | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	16.00%
Corporate | Trading and investment securities | Internal Model | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Interest Rate (as a percent)	0.35%
Equity Volatility	14.41%
Corporate | Trading and investment securities | Internal Model | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Interest Rate (as a percent)	16.38%
Price	126.97
Equity Volatility	55.49%
Equity securities | Trading and investment securities
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of assets as of the balance sheet date	1,517,000,000
Equity securities | Trading and investment securities | Cash flow | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	5.00%
Recovery Rate (as a percent)	10.00%
WAL	3
Equity securities | Trading and investment securities | Cash flow | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	15.00%
Recovery Rate (as a percent)	100.00%
WAL	3
Equity securities | Trading and investment securities | Price-based | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Price	115.00
Equity securities | Trading and investment securities | Internal Model | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Equity Volatility	8.10%
Equity securities | Trading and investment securities | Internal Model | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Equity Volatility	241.80%
Asset-backed securities | Trading and investment securities
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of assets as of the balance sheet date	8,729,000,000
Asset-backed securities | Trading and investment securities | Cash flow | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Credit Correlation	0.2000
Asset-backed securities | Trading and investment securities | Cash flow | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Credit Correlation	0.6000
Asset-backed securities | Trading and investment securities | Price-based | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Price	0.00
WAL	1.44
Asset-backed securities | Trading and investment securities | Price-based | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Price	127.86
Recovery Rate (as a percent)	100.00%
WAL	21.42
Asset-backed securities | Trading and investment securities | Internal Model | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	0.55%
Asset-backed securities | Trading and investment securities | Internal Model | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	30.67%
Other debt securities | Trading and investment securities
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of assets as of the balance sheet date	2,642,000,000
Other debt securities | Trading and investment securities | Cash flow | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Credit Spread (as a percent)	0.22%
Other debt securities | Trading and investment securities | Cash flow | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Credit Spread (as a percent)	7.03%
Other debt securities | Trading and investment securities | Price-based | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Recovery Rate (as a percent)	40.00%
WAL	1.44
Other debt securities | Trading and investment securities | Price-based | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Price	110.27
Recovery Rate (as a percent)	40.00%
WAL	21.42
Other debt securities | Trading and investment securities | Internal Model | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	1.75%
Other debt securities | Trading and investment securities | Internal Model | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	14.40%
Non-marketable equity securities | Trading and investment securities
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of assets as of the balance sheet date	8,268,000,000
Non-marketable equity securities | Trading and investment securities | Cash flow | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Adjustment factor	0.5
Non-marketable equity securities | Trading and investment securities | Price-based | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
EBITDA multiples	0.70
Non-marketable equity securities | Trading and investment securities | Price-based | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Price	3.70
EBITDA multiples	13.55
Non-marketable equity securities | Trading and investment securities | Comparables Analysis | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	9.09%
Non-marketable equity securities | Trading and investment securities | Comparables Analysis | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	12.00%
Securities sold, not yet purchased | Trading account liabilities
Fair Value Inputs Assets Liabilities Quantitative Information
Fair value of liabilities as of the balance sheet date	177,000,000
Securities sold, not yet purchased | Trading account liabilities | Cash flow | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Yield (as a percent)	30.67%
Securities sold, not yet purchased | Trading account liabilities | Price-based | Minimum
Fair Value Inputs Assets Liabilities Quantitative Information
WAL	1.44
Securities sold, not yet purchased | Trading account liabilities | Price-based | Maximum
Fair Value Inputs Assets Liabilities Quantitative Information
Price	105.01
WAL	21.42