Goodwill and Other Intangible Assets - Changes in the Carrying Amounts of Other Intangible Assets (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013		Dec. 31, 2013	Dec. 31, 2012
Servicing Asset at Fair Value, Amount	$ 1,251				$ 1,300
Amortization	(3)		(6)
Origination of Mortgage Servicing Rights (MSRs)	32		110
Due to changes in inputs or assumptions	(46)	[1]	90	[1]
Servicing Asset at Fair Value, Other Changes in Fair Value	(35)	[2]	(74)	[2]
Ending Balance	1,282		1,076		1,334	956
Mortgage Servicing Rights, Fair Value [Member]
Servicing Asset at Fair Value, Amount	1,251		1,025		1,300	899
Amortization	0		0
Origination of Mortgage Servicing Rights (MSRs)	32		110
Due to changes in inputs or assumptions	(46)	[1]	90	[1]
Servicing Asset at Fair Value, Other Changes in Fair Value	(35)	[2]	(74)	[2]
Other Intangible Assets [Member]
Amortization	(2)		(3)
Origination of Mortgage Servicing Rights (MSRs)	0		0
Due to changes in inputs or assumptions	0		0
Servicing Asset at Fair Value, Other Changes in Fair Value	0		0
Ending Balance	28		37		30	40
Core Deposits [Member]
Amortization	(1)		(3)
Origination of Mortgage Servicing Rights (MSRs)	0		0
Due to changes in inputs or assumptions	0		0
Servicing Asset at Fair Value, Other Changes in Fair Value	0		0
Ending Balance	$ 3		$ 14		$ 4	$ 17

[1] Primarily reflects changes in discount rates and prepayment speed assumptions, due to changes in interest rates.

[2] Represents changes due to the collection of expected cash flows, net of accretion, due to the passage of time.