Derivative Financial Instruments - Additional Information (Detail) (USD $)				3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 Credit Risk Derivative [Member]	Mar. 31, 2014 Interest rate swap agreements [Member]	Mar. 31, 2013 Interest rate swap agreements [Member]	Mar. 31, 2014 Interest rate contracts [Member]	Dec. 31, 2013 Interest rate contracts [Member]	Mar. 31, 2014 Foreign Currency And Other Option And Futures Contracts [Member]	Dec. 31, 2013 Foreign Currency And Other Option And Futures Contracts [Member]
Derivative [Line Items]
Increase in net interest income due to interest rate swap agreements				$ 11,000,000	$ 10,000,000
Notional value of interest rate contracts entered into trading purposes						17,100,000,000	17,400,000,000	1,000,000,000	1,400,000,000
Net unrealized pre-tax gains related to hedged loans held for sale, commitments to originate loans for sale and commitments to sell loans	23,000,000	23,000,000
Aggregate fair value of derivative financial instruments in a liability position	175,000,000	194,000,000
Net liability positions with counterparties	101,000,000	107,000,000
Post collateral requirements relating to positions	93,000,000	95,000,000
Aggregate fair value of derivative financial instruments in a net liability position			32,000,000
Fair value of collateral already posted for derivative financial instruments			22,000,000
Fair value of additional collateral to be posted for derivative financial instruments			10,000,000
Aggregate fair value of derivative financial instruments in asset position	167,000,000	183,000,000
Net asset positions with counterparties	94,000,000	95,000,000
Counterparties posted collateral relating to positions	$ 92,000,000	$ 93,000,000