Impacts of Derivative Financial Instruments on the Consolidated Statements of Income/(Loss) and the Consolidated Statements of Shareholders' Equity (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Cash Flow Hedging | Interest Income, Interest and Fees on Loans | Interest Rate Contract [Member] | Floating Rate Loans
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	$ 125		$ 23
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	35	[1]	76	[2]
Fair Value Hedging
Derivative Instruments, Gain (Loss) Recognized in Income, Net	14	[3]
Amount of gain on related Hedged Items recognized in Income	(14)	[3]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0	[3]
Fair Value Hedging | Trading Account Profits And Commissions [Member] | Interest Rate Contract [Member] | Available-for-sale Securities [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net	0
Amount of gain on related Hedged Items recognized in Income	0
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0
Fair Value Hedging | Trading Account Profits And Commissions [Member] | Interest Rate Contract [Member] | Fixed Rate Debt
Derivative Instruments, Gain (Loss) Recognized in Income, Net	14	[3]	9	[3]
Amount of gain on related Hedged Items recognized in Income	(14)	[3]	(9)	[3]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0		0
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net	206		105
Not Designated as Hedging Instrument [Member] | Trading Account Profits And Commissions [Member] | Interest Rate Contract [Member] | Trading Activity
Derivative Instruments, Gain (Loss) Recognized in Income, Net	15		14
Not Designated as Hedging Instrument [Member] | Trading Account Profits And Commissions [Member] | Foreign Exchange Contract | Trading Activity
Derivative Instruments, Gain (Loss) Recognized in Income, Net	56		5
Not Designated as Hedging Instrument [Member] | Trading Account Profits And Commissions [Member] | Credit Risk Contract [Member] | Trading Activity
Derivative Instruments, Gain (Loss) Recognized in Income, Net	6		4
Not Designated as Hedging Instrument [Member] | Trading Account Profits And Commissions [Member] | Equity Contract [Member] | Trading Activity
Derivative Instruments, Gain (Loss) Recognized in Income, Net	3		1
Not Designated as Hedging Instrument [Member] | Mortgage Servicing Income [Member] | Interest Rate Contract [Member] | Mortgage Servicing Rights [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net	88		55
Not Designated as Hedging Instrument [Member] | Mortgage Production Income [Member] | Interest Rate Contract [Member] | Loans
Derivative Instruments, Gain (Loss) Recognized in Income, Net	(43)		(34)
Not Designated as Hedging Instrument [Member] | Mortgage Production Income [Member] | Other Contract | Loans
Derivative Instruments, Gain (Loss) Recognized in Income, Net	$ 81		$ 60

[1] During the three months ended March 31, 2015, the Company also reclassified $19 million of pre-tax gains from AOCI into net interest income. These gains related to hedging relationships that have been previously terminated or de-designated and are reclassified into earnings consistent with the pattern of net cash flows expected to be recognized.

[2] During the three months ended March 31, 2014, the Company also reclassified $26 million pre-tax gains from AOCI into net interest income. These gains related to hedging relationships that have been previously terminated or de-designated and are reclassified into earnings consistent with the pattern of net cash flows expected to be recognized.

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