Fair Value Measurement- Quantitative Information about Level 3 Fair Value Measurements of Assets (Detail) (USD $) In Millions, unless otherwise specified							3 Months Ended					3 Months Ended										3 Months Ended						3 Months Ended
	Mar. 31, 2014 Fair Value, Measurements, Recurring Level 3	Dec. 31, 2013 Fair Value, Measurements, Recurring Level 3	Mar. 31, 2014 Fair Value, Measurements, Nonrecurring	Dec. 31, 2013 Fair Value, Measurements, Nonrecurring	Mar. 31, 2014 Fair Value, Measurements, Nonrecurring Level 3	Dec. 31, 2013 Fair Value, Measurements, Nonrecurring Level 3	Mar. 31, 2014 Trading Liabilities Fair Value, Measurements, Recurring Level 3 Structured Foreign Exchange Swaptions Option Pricing Model Minimum	Mar. 31, 2014 Trading Liabilities Fair Value, Measurements, Recurring Level 3 Structured Foreign Exchange Swaptions Option Pricing Model Maximum	Mar. 31, 2014 Trading Liabilities Fair Value, Measurements, Recurring Level 3 Equity Options Option Pricing Model Minimum	Mar. 31, 2014 Trading Liabilities Fair Value, Measurements, Recurring Level 3 Equity Options Option Pricing Model Maximum	Mar. 31, 2014 Securities available-for-sale Fair Value, Measurements, Recurring Level 3 State and political subdivisions Discounted Cash Flow	Mar. 31, 2014 Securities available-for-sale Fair Value, Measurements, Recurring Level 3 State and political subdivisions Discounted Cash Flow Minimum	Mar. 31, 2014 Securities available-for-sale Fair Value, Measurements, Recurring Level 3 State and political subdivisions Discounted Cash Flow Maximum	Mar. 31, 2014 Trading Securities Fair Value, Measurements, Recurring Level 3 Distressed Debt Discounted Cash Flow Minimum	Mar. 31, 2014 Trading Securities Fair Value, Measurements, Recurring Level 3 Distressed Debt Discounted Cash Flow Maximum	Mar. 31, 2014 Trading Securities Fair Value, Measurements, Recurring Level 3 Structured Foreign Exchange Swaptions Option Pricing Model Minimum	Mar. 31, 2014 Trading Securities Fair Value, Measurements, Recurring Level 3 Structured Foreign Exchange Swaptions Option Pricing Model Maximum	Mar. 31, 2014 Trading Securities Fair Value, Measurements, Recurring Level 3 Long-Term Foreign Exchange Options Option Pricing Model		Mar. 31, 2014 Trading Securities Fair Value, Measurements, Recurring Level 3 Equity Options Option Pricing Model		Mar. 31, 2014 Trading Securities Fair Value, Measurements, Recurring Level 3 Equity Options Option Pricing Model Minimum	Mar. 31, 2014 Trading Securities Fair Value, Measurements, Recurring Level 3 Equity Options Option Pricing Model Maximum	Mar. 31, 2014 Loans Receivable Fair Value, Measurements, Nonrecurring Level 3	Mar. 31, 2014 Loans Receivable Fair Value, Measurements, Nonrecurring Level 3 Minimum	Mar. 31, 2014 Loans Receivable Fair Value, Measurements, Nonrecurring Level 3 Maximum	Mar. 31, 2014 Loans Receivable Fair Value, Measurements, Nonrecurring Level 3 Discounted Cash Flow	Mar. 31, 2014 Loans Receivable Fair Value, Measurements, Nonrecurring Level 3 Discounted Cash Flow Minimum	Mar. 31, 2014 Loans Receivable Fair Value, Measurements, Nonrecurring Level 3 Discounted Cash Flow Maximum	Mar. 31, 2014 Debt and equity instruments Trading Securities Fair Value, Measurements, Recurring Level 3 Distressed Debt Discounted Cash Flow	Mar. 31, 2014 Derivative assets Trading Securities Fair Value, Measurements, Recurring Level 3 Structured Foreign Exchange Swaptions Option Pricing Model
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value inputs, expected credit loss (percent)												4.00%	4.00%
Fair value of assets	$ 141	$ 139	$ 145	$ 152	$ 7	$ 9					$ 11							$ 1	[1]	$ 13	[1]						$ 7			$ 1	$ 5	[1]
Expected maturity														1 year	10 years
Credit spreads (percent)														1.26%	28.79%
Correlation risk (percent)							0.00%	25.00%								0.00%	25.00%
Volatility (percent)							10.00%	17.00%	19.00%	26.00%						10.00%	17.00%	18.00%				17.00%	25.00%
Timing of sale																									0 months	12 months
Cap rate (percent)																								8.00%
Cost to complete/sell (percent)																												0.00%	30.00%

[1] The option pricing model uses market inputs such as foreign currency exchange rates, interest rates and volatility to calculate the fair value of the option.