Fair Value Measurements - Quantitative Information about Recurring Fair Value Measurement of Assets and Liabilities Classified as Level 3 (Detail) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2013		Dec. 31, 2012
Equity / Equity Index volatility [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Equity / Equity Index volatility
Equity / Equity and Equity / Index correlation
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Equity / Equity and Equity / Index correlation
Minimum [Member] | Collateralized debt obligations [Member] | Broker quotes or consensus pricing and, where applicable, discounted cash flows [Member] | Prepayment rates [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	0.00%		0.00%
Minimum [Member] | Collateralized debt obligations [Member] | Broker quotes or consensus pricing and, where applicable, discounted cash flows [Member] | Constant default rates [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	4.00%		4.00%
Minimum [Member] | Collateralized debt obligations [Member] | Broker quotes or consensus pricing and, where applicable, discounted cash flows [Member] | Loss Severity Rates [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	50.00%		50.00%
Minimum [Member] | Corporate and other domestic [Member] | Discounted cash flows [Member] | Spread volatility on collateral assets [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	1.10%		1.50%
Minimum [Member] | Foreign debt securities [Member] | Discounted cash flows [Member] | Correlations of default among a portfolio of credit names of embedded credit derivatives [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	34.30%		28.56%
Minimum [Member] | Equity securities [Member] | Net asset value of hedge funds [Member] | Range of fair value adjustments to reflect restrictions on timing and amount of redemption and realization risks [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	30.00%		30.00%
Minimum [Member] | Interest rate contracts [Member] | Market Comparable Adjusted For Probability To Fund [Member] | Probability to fund for rate lock commitments [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	8.00%		8.00%
Minimum [Member] | Foreign exchange contracts [Member] | Option pricing model [Member] | Implied volatility of currency pairs [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	1.60%		1.60%
Minimum [Member] | Equity contracts [Member] | Option pricing model [Member] | Equity / Equity Index volatility [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	5.00%		6.00%
Minimum [Member] | Equity contracts [Member] | Option pricing model [Member] | Equity / Equity and Equity / Index correlation
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	52.00%		56.00%
Minimum [Member] | Credit Derivative Contracts [Member] | Option pricing model [Member] | Correlation of defaults of a portfolio of reference credit names [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	36.30%		32.04%
Minimum [Member] | Credit Derivative Contracts [Member] | Option pricing model [Member] | Industry by industry correlation of defaults [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	48.00%		44.00%
Minimum [Member] | Mortgage servicing rights [Member] | Option adjusted discounted cash flows [Member] | Constant prepayment rates [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	7.30%		8.50%
Minimum [Member] | Mortgage servicing rights [Member] | Option adjusted discounted cash flows [Member] | Option adjusted spread [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	8.07%		8.07%
Minimum [Member] | Mortgage servicing rights [Member] | Option adjusted discounted cash flows [Member] | Estimated annualized costs to service [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of inputs per account	91		98
Minimum [Member] | Deposits In Domestic Offices [Member] | Option adjusted discounted cash flows [Member] | Equity / Equity Index volatility [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	5.00%		6.00%
Minimum [Member] | Deposits In Domestic Offices [Member] | Option adjusted discounted cash flows [Member] | Equity / Equity and Equity / Index correlation
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	52.00%		56.00%
Minimum [Member] | Deposits In Domestic Offices [Member] | Option adjusted discounted cash flows [Member] | Implied volatility of currency pairs [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	1.60%		1.60%
Minimum [Member] | Long-term Debt [Member] | Option adjusted discounted cash flows [Member] | Equity / Equity Index volatility [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	5.00%		6.00%
Minimum [Member] | Long-term Debt [Member] | Option adjusted discounted cash flows [Member] | Equity / Equity and Equity / Index correlation
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	52.00%		56.00%
Minimum [Member] | Long-term Debt [Member] | Option adjusted discounted cash flows [Member] | Implied volatility of currency pairs [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	1.60%		1.60%
Maximum [Member] | Collateralized debt obligations [Member] | Broker quotes or consensus pricing and, where applicable, discounted cash flows [Member] | Prepayment rates [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	6.00%		6.00%
Maximum [Member] | Collateralized debt obligations [Member] | Broker quotes or consensus pricing and, where applicable, discounted cash flows [Member] | Constant default rates [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	11.00%		14.00%
Maximum [Member] | Collateralized debt obligations [Member] | Broker quotes or consensus pricing and, where applicable, discounted cash flows [Member] | Loss Severity Rates [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	95.00%		100.00%
Maximum [Member] | Corporate and other domestic [Member] | Discounted cash flows [Member] | Spread volatility on collateral assets [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	4.00%		4.00%
Maximum [Member] | Foreign debt securities [Member] | Discounted cash flows [Member] | Correlations of default among a portfolio of credit names of embedded credit derivatives [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	34.40%		28.57%
Maximum [Member] | Equity securities [Member] | Net asset value of hedge funds [Member] | Range of fair value adjustments to reflect restrictions on timing and amount of redemption and realization risks [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	100.00%		100.00%
Maximum [Member] | Interest rate contracts [Member] | Market Comparable Adjusted For Probability To Fund [Member] | Probability to fund for rate lock commitments [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	100.00%		100.00%
Maximum [Member] | Foreign exchange contracts [Member] | Option pricing model [Member] | Implied volatility of currency pairs [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	20.90%		20.90%
Maximum [Member] | Equity contracts [Member] | Option pricing model [Member] | Equity / Equity Index volatility [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	120.00%		104.00%
Maximum [Member] | Equity contracts [Member] | Option pricing model [Member] | Equity / Equity and Equity / Index correlation
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	61.00%		64.00%
Maximum [Member] | Credit Derivative Contracts [Member] | Option pricing model [Member] | Correlation of defaults of a portfolio of reference credit names [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	45.80%		45.31%
Maximum [Member] | Credit Derivative Contracts [Member] | Option pricing model [Member] | Industry by industry correlation of defaults [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	75.00%		67.00%
Maximum [Member] | Mortgage servicing rights [Member] | Option adjusted discounted cash flows [Member] | Constant prepayment rates [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	33.10%		44.80%
Maximum [Member] | Mortgage servicing rights [Member] | Option adjusted discounted cash flows [Member] | Option adjusted spread [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	19.07%		19.07%
Maximum [Member] | Mortgage servicing rights [Member] | Option adjusted discounted cash flows [Member] | Estimated annualized costs to service [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of inputs per account	256		263
Maximum [Member] | Deposits In Domestic Offices [Member] | Option adjusted discounted cash flows [Member] | Equity / Equity Index volatility [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	120.00%		104.00%
Maximum [Member] | Deposits In Domestic Offices [Member] | Option adjusted discounted cash flows [Member] | Equity / Equity and Equity / Index correlation
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	61.00%		64.00%
Maximum [Member] | Deposits In Domestic Offices [Member] | Option adjusted discounted cash flows [Member] | Implied volatility of currency pairs [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	20.90%		20.90%
Maximum [Member] | Long-term Debt [Member] | Option adjusted discounted cash flows [Member] | Equity / Equity Index volatility [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	120.00%		104.00%
Maximum [Member] | Long-term Debt [Member] | Option adjusted discounted cash flows [Member] | Equity / Equity and Equity / Index correlation
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	61.00%		64.00%
Maximum [Member] | Long-term Debt [Member] | Option adjusted discounted cash flows [Member] | Implied volatility of currency pairs [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	20.90%		20.90%
Weighted Average [Member] | Corporate and other domestic [Member] | Discounted cash flows [Member] | Correlation between insurance claim shortfall and collateral value [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Range of Inputs	80.00%		80.00%
Recurring [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Equity / Equity Index volatility	[1],[2]
Recurring [Member] | Level 3 [Member] | Prepayment rates [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Prepayment rates
Recurring [Member] | Level 3 [Member] | Constant default rates [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Conditional default rates
Recurring [Member] | Level 3 [Member] | Loss Severity Rates [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Loss severity rates
Recurring [Member] | Level 3 [Member] | Spread volatility on collateral assets [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Spread volatility on collateral assets
Recurring [Member] | Level 3 [Member] | Correlation between insurance claim shortfall and collateral value [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Correlation between insurance claim shortfall and collateral value
Recurring [Member] | Level 3 [Member] | Correlations of default among a portfolio of credit names of embedded credit derivatives [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Correlations of default among a portfolio of credit names of embedded credit derivatives
Recurring [Member] | Level 3 [Member] | Range of fair value adjustments to reflect restrictions on timing and amount of redemption and realization risks [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Range of fair value adjustments to reflect restrictions on timing and amount of redemption and realization risks
Recurring [Member] | Level 3 [Member] | Probability to fund for rate lock commitments [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Probability to fund for rate lock commitments
Recurring [Member] | Level 3 [Member] | Implied volatility of currency pairs [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Implied volatility of currency pairs	[2]
Recurring [Member] | Level 3 [Member] | Equity / Equity Index volatility [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Equity / Equity Index volatility	[1],[2]
Recurring [Member] | Level 3 [Member] | Equity / Equity and Equity / Index correlation
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Equity / Equity and Equity / Index correlation	[1],[2]
Recurring [Member] | Level 3 [Member] | Correlation of defaults of a portfolio of reference credit names [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Correlation of defaults of a portfolio of reference credit names
Recurring [Member] | Level 3 [Member] | Industry by industry correlation of defaults [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Industry by industry correlation of defaults
Recurring [Member] | Level 3 [Member] | Constant prepayment rates [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Constant prepayment rates
Recurring [Member] | Level 3 [Member] | Option adjusted spread [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Option adjusted spread
Recurring [Member] | Level 3 [Member] | Estimated annualized costs to service [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Estimated annualized costs to service
Recurring [Member] | Level 3 [Member] | Implied volatility of currency pairs [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Implied volatility of currency pairs	[1],[2]
Recurring [Member] | Level 3 [Member] | Broker quotes or consensus pricing and, where applicable, discounted cash flows [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Broker quotes or consensus pricing and, where applicable, discounted cash flows
Recurring [Member] | Level 3 [Member] | Discounted cash flows [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Discounted cash flows
Recurring [Member] | Level 3 [Member] | Net asset value of hedge funds [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Net asset value of hedge funds
Recurring [Member] | Level 3 [Member] | Market Comparable Adjusted For Probability To Fund [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Market comparable adjusted for probability to fund
Recurring [Member] | Level 3 [Member] | Option pricing model [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Option pricing model	[2]
Recurring [Member] | Level 3 [Member] | Option adjusted discounted cash flows [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Inputs	Option adjusted discounted cash flows	[1],[2]
Recurring [Member] | Level 3 [Member] | Collateralized debt obligations [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value	481,000,000		466,000,000
Recurring [Member] | Level 3 [Member] | Corporate and other domestic [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value	1,524,000,000		1,861,000,000
Recurring [Member] | Level 3 [Member] | Foreign debt securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value	437,000,000		610,000,000
Recurring [Member] | Level 3 [Member] | Equity securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value	11,000,000		9,000,000
Recurring [Member] | Level 3 [Member] | Interest rate contracts [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value	6,000,000		7,000,000
Recurring [Member] | Level 3 [Member] | Foreign exchange contracts [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value	134,000,000	[2]	5,000,000	[2]
Recurring [Member] | Level 3 [Member] | Equity contracts [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value	34,000,000	[2]	(7,000,000)	[2]
Recurring [Member] | Level 3 [Member] | Credit Derivative Contracts [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value	364,000,000		571,000,000
Recurring [Member] | Level 3 [Member] | Mortgage servicing rights [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value	190,000,000		168,000,000
Recurring [Member] | Level 3 [Member] | Deposits In Domestic Offices [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value	(2,876,000,000)		(2,636,000,000)	[1],[2]
Recurring [Member] | Level 3 [Member] | Long-term Debt [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value	(618,000,000)	[1],[2]	(429,000,000)

[1] Structured deposits and structured notes contain embedded derivative features whose fair value measurements contain significant Level 3 inputs.

[2] We are the client-facing entity and we enter into identical but opposite derivatives to transfer the resultant risks to our affiliates. With the exception of counterparty credit risks, we are market neutral. The corresponding intra-group derivatives are presented as equity derivatives and foreign currency derivatives in the table.