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				9 Months Ended
	Sep. 30, 2017		Sep. 30, 2016		Sep. 30, 2017		Sep. 30, 2016
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 50		$ 155		$ 136		$ 526
Other Trading [Member] | Other Trading [Member]
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	11		11		33		24
Other Trading [Member] | Foreign Exchange Contract [Member]
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	(10)		36		(43)		52
Other Trading [Member] | Credit Risk Contract [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	8		5		19		14
Other Trading [Member] | Equity Contract [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(1)		1		(1)		5
Other Trading [Member] | Commodity Contract [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	0		1		1		2
Mortgage Servicing Income [Member] | Mortgage Servicing Rights [Member]
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	14		15		34		306
Mortgage Production Income [Member] | Loans Held For Sale [Member]
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	(20)		(35)		(57)		(162)
Mortgage Production Income [Member] | Other Contract [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	49		122		154		291
Other Income [Member] | Loans [Member]
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	0		0		(1)		(3)
Other Income [Member] | Credit Risk Contract [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(1)		(1)		(3)		(3)
Cash Flow Hedging [Member] | Interest Income [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	10	[1]	(78)	[2]	61	[1]	408	[2]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	3	[1]	36	[2]	37	[1]	113	[2]
Fair Value Hedging [Member] | Other Trading [Member]
Derivative, Gain (Loss) on Derivative, Net	(3)		(10)		5		20
Gain (Loss) on Fair Value Hedges Recognized in Earnings	3		11		(4)		(19)
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	0		1		1		1
Fair Value Hedging [Member] | Other Trading [Member] | Fixed Income Interest Rate [Member]
Derivative, Gain (Loss) on Derivative, Net	(3)	[3]	(10)	[4]	5	[3]	20	[4]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	3	[3]	11	[4]	(4)	[3]	(19)	[4]
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	0	[3]	1	[4]	1	[3]	1	[4]
Fair Value Hedging [Member] | Other Trading [Member] | Brokered Time Deposits [Member]
Derivative, Gain (Loss) on Derivative, Net	0	[3]	0	[4]	0	[3]	0	[4]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	0	[3]	0	[4]	0	[3]	0	[4]
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	$ 0	[3]	$ 0	[4]	$ 0	[3]	$ 0	[4]

[1] During the three and nine months ended September 30, 2017, the Company also reclassified $10 million and $44 million of pre-tax gains from AOCI into net interest income, respectively. These gains related to hedging relationships that have been terminated and are reclassified into earnings consistent with the pattern of net cash flows expected to be recognized.

[2] During the three and nine months ended September 30, 2016, the Company also reclassified $23 million and $77 million of pre-tax gains from AOCI into net interest income, respectively. These gains related to hedging relationships that have been terminated 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.

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