Derivative Instruments- Impact of Derivative Instruments on Income Statement (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Fair Value Hedging | Interest rate contracts | Net interest revenue
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (loss) recognized in income on derivatives	$ (285)	$ 98	$ 75
Gain or (loss) recognized in hedged item	277	(94)	(71)
Cash flow hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (loss) recognized in accumulated OCI on derivatives (effective portion)	6	4	171
Gain or (loss) reclassified from accumulated OCI into income (effective portion)	4	1	170
Gain or (loss) recognized in income on derivatives (ineffectiveness portion and amount excluded from effectiveness testing)	0.1	0	0.1
Cash flow hedges | Foreign exchange contracts | Net interest revenue
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (loss) recognized in accumulated OCI on derivatives (effective portion)	(1)	(4)	(12)
Gain or (loss) reclassified from accumulated OCI into income (effective portion)	(1)	(4)	(13)
Gain or (loss) recognized in income on derivatives (ineffectiveness portion and amount excluded from effectiveness testing)	0	0	0
Cash flow hedges | Foreign exchange contracts | Other revenue
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (loss) recognized in accumulated OCI on derivatives (effective portion)	3	1	2
Gain or (loss) reclassified from accumulated OCI into income (effective portion)	0	0	0
Gain or (loss) recognized in income on derivatives (ineffectiveness portion and amount excluded from effectiveness testing)	0.1	0	0.1
Cash flow hedges | Foreign exchange contracts | Trading revenue
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (loss) recognized in accumulated OCI on derivatives (effective portion)	3	4	183
Gain or (loss) reclassified from accumulated OCI into income (effective portion)	3	4	183
Gain or (loss) recognized in income on derivatives (ineffectiveness portion and amount excluded from effectiveness testing)	0	0	0
Cash flow hedges | Foreign exchange contracts | Salary expense
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (loss) recognized in accumulated OCI on derivatives (effective portion)	1	3	(2)
Gain or (loss) reclassified from accumulated OCI into income (effective portion)	2	1	0
Gain or (loss) recognized in income on derivatives (ineffectiveness portion and amount excluded from effectiveness testing)	0	0	0
Net Investment Hedging | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (loss) recognized in accumulated OCI on derivatives (effective portion)	(16)	(63)	167
Net Investment Hedging | Foreign exchange contracts | Net interest revenue
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (loss) reclassified from accumulated OCI into income (effective portion)	0	0	0
Net Investment Hedging | Foreign exchange contracts | Other revenue
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (loss) recognized in income on derivatives (ineffectiveness portion and amount excluded from effectiveness testing)	$ (0.1)	$ 0	$ (0.1)