Derivative Financial Instruments - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative Liability, Fair Value, Gross Liability	$ 5,577,000,000	$ 5,673,000,000
Derivative Asset, Fair Value, Gross Asset	5,839,000,000	6,125,000,000
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net			60,000,000
Executed equity forward agreement underlying shares			60,000,000
Contributed equity forward agreement underlying shares			1,000,000
Net gain on sales of certain other equity securities			1,900,000,000
Sold equity forward agreement underlying shares			59,000,000
Gain (Loss) on Contract Termination			305,000,000
Cash Flow Hedging
Deferred net gains on derivatives that are recorded in AOCI are expected to be reclassified to net interest income over the next twelve months in connection with the recognition of interest income or interest expense on these hedged items	203,000,000
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		327,000,000	(28,000,000)
written risk participations [Member]
Minimum Term of Credit Risk Derivatives	1 year	1 year
Maximum Term of Credit Risk Derivatives	9 years	12 years
Weighted Average Term of Credit Risk Derivatives	5.2	6.9
Credit and Market Risk
Derivative asset positions	1,096,000,000	1,000,000,000
Net derivative asset positions to which the Company was exposed to risk of its counterparties, netted by counterparty where formal netting arrangements exist	1,500,000,000	1,500,000,000
Collateral Held by The Company Against Derivative Asset Positions	386,000,000	523,000,000
Adjusted the fair value of its net derivative asset position for estimates of counterparty credit risk	7,000,000	13,000,000
Derivative Liability, Fair Value, Gross Liability	1,092,000,000	941,000,000
Credit and Market Risk | Additional Termination Event [Member]
Derivative Liability, Fair Value, Gross Liability	1,000,000
Credit and Market Risk | Additional Termination Event [Member] | Credit Downgrade [Member]
Derivative Liability, Fair Value, Gross Liability	27,000,000
Credit and Market Risk | Credit Support Annex
Derivative Liability, Fair Value, Gross Liability	1,066,000,000
Derivative Liability, Fair Value of Collateral	1,022,000,000
Credit and Market Risk | Credit Support Annex | Credit Downgrade [Member]
Posted collateral	20,000,000
Credit Default Swap
Maximum Term of Credit Risk Derivatives	4 years	4 years
Maximum exposure	20,000,000	60,000,000
Derivative, Notional Amount	190,000,000	70,000,000
Credit Risk Derivatives, at Fair Value, Net	5,000,000	3,000,000
Credit Derivatives Swap Participation
Maximum exposure	31,000,000	33,000,000
Credit Risk Derivatives, at Fair Value, Net	1,000,000	1,000,000
Cash Flow Derivatives Hedges [Member]
Derivative, Lower Remaining Maturity Range	1 year	1 year
Derivative, Higher Remaining Maturity Range	4 years	5 years
Weighted Average of Maturities of Cash Flow Hedges	1.9	2.0
Total Return Swap
Derivative Liability, Fair Value, Gross Liability	14,000,000	31,000,000
Derivative, Notional Amount	2,300,000,000	1,500,000,000
Derivative Asset, Fair Value, Gross Asset	19,000,000	35,000,000
Collateral held	373,000,000	228,000,000
Derivatives Sold | Credit Default Swap
Credit Risk Derivatives, at Fair Value, Net	1,000,000	3,000,000
Interest Income (Expense), Net [Member]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	97,000,000	90,000,000	171,000,000
Available-for-sale Securities [Member] | Equity Contract [Member] | Cash Flow Hedging
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net			$ (365,000,000)	[1]

[1] Amounts are recognized in trading income in the Consolidated Statements of Income.