Impacts of Derivative Financial Instruments on the Consolidated Statements of Income/(Loss) and the Consolidated Statements of Shareholders' Equity (Detail) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2015		Jun. 30, 2014		Jun. 30, 2015		Jun. 30, 2014
Fair Value Hedging
Derivative Instruments, Gain (Loss) Recognized in Income, Net	[1]	$ (8)				$ 7
Amount of gain on related Hedged Items recognized in Income	[1]	7				(7)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	[1]	(1)				0
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	[1]			0
Amount of gain on related Hedged Items recognized in Income		0	[1]			0
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		0	[1]			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		(8)	[1]	$ 8	[2]	7	[1]	$ 17	[2]
Amount of gain on related Hedged Items recognized in Income		7	[1]	(7)	[2]	(7)	[1]	(16)	[2]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		(1)	[1]	1		0		1
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net		(86)		93		120		198
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		25		11		40		25
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		(20)		(7)		36		(1)
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		7		4		13		9
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		0		2		3		3
Not Designated as Hedging Instrument [Member] | Trading Account Profits And Commissions [Member] | Other Contract | Trading Activity
Derivative Instruments, Gain (Loss) Recognized in Income, Net		1				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		(163)		66		(74)		120
Not Designated as Hedging Instrument [Member] | Mortgage Production Income [Member] | Interest Rate Contract [Member] | Loans [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net		52		(61)		9		(95)
Not Designated as Hedging Instrument [Member] | Mortgage Production Income [Member] | Other Contract | Loans [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net		12		78		93		138
Not Designated as Hedging Instrument [Member] | Other Income [Member] | Credit Risk Contract [Member] | Loans [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net		$ 0		$ 0		$ (1)		$ (1)

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

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