Notional Amounts and Fair Values for All Derivative Instruments Included in the Consolidated Balance Sheets (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	$ 1,972	$ 2,356
Fair value - Derivative Liabilities	915	1,344
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	640	812
Fair value - Derivative Liabilities	1	5
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Fair Value Hedging
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	558	662
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Fair Value Hedging | Interest Rate Swap | Long-Term Debt
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	558	662
Notional amount	2,880	4,080
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Cash Flow Hedging
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	82	150
Fair value - Derivative Liabilities	1	5
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Cash Flow Hedging | Interest Rate Swap | Long-Term Debt
Derivatives, Fair Value [Line Items]
Fair value - Derivative Liabilities	1	5
Notional amount	250	250
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Cash Flow Hedging | Interest Rate Swap | Commercial And Industrial Loans [Member]
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	60	59
Notional amount	1,000	1,500
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Cash Flow Hedging | Interest Rate Floor | Commercial And Industrial Loans [Member]
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	22	91
Notional amount	1,500	1,500
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Cash Flow Hedging | Interest Rate Cap | Long-Term Debt
Derivatives, Fair Value [Line Items]
Notional amount	500	500
Nondesignated
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	1,332	1,544
Fair value - Derivative Liabilities	914	1,339
Nondesignated | Risk Management and Other Business Purposes
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	398	307
Fair value - Derivative Liabilities	47	136
Nondesignated | Risk Management and Other Business Purposes | Interest Rate Swap | Long-Term Debt
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets		1
Fair value - Derivative Liabilities		3
Notional amount		311
Nondesignated | Risk Management and Other Business Purposes | Interest Rate Contract | Mortgage Servicing Rights
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	219	187
Notional amount	10,177	3,077
Nondesignated | Risk Management and Other Business Purposes | Forward Contracts | Assets Held-for-sale
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	2	8
Fair value - Derivative Liabilities	14	54
Notional amount	5,322	5,705
Nondesignated | Risk Management and Other Business Purposes | Put Option
Derivatives, Fair Value [Line Items]
Fair value - Derivative Liabilities		1
Notional amount		978
Nondesignated | Risk Management and Other Business Purposes | Warrant [Member]
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	177	111
Notional amount	416	223
Nondesignated | Risk Management and Other Business Purposes | Swap [Member]
Derivatives, Fair Value [Line Items]
Fair value - Derivative Liabilities	33	78
Notional amount	644	436
Nondesignated | Customer Accommodation [Member]
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	934	1,237
Fair value - Derivative Liabilities	867	1,203
Nondesignated | Customer Accommodation [Member] | Interest Rate Contract
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	586	774
Fair value - Derivative Liabilities	602	795
Notional amount	27,354	30,000
Nondesignated | Customer Accommodation [Member] | Foreign Exchange Contract
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	201	294
Fair value - Derivative Liabilities	183	275
Notional amount	17,297	17,909
Nondesignated | Customer Accommodation [Member] | Interest Rate Lock Commitments [Member]
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	60	33
Fair value - Derivative Liabilities		1
Notional amount	4,894	3,835
Nondesignated | Customer Accommodation [Member] | Commodity Contract
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	87	134
Fair value - Derivative Liabilities	82	130
Notional amount	3,084	2,074
Nondesignated | Customer Accommodation [Member] | Derivative | Certificates of Deposit
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets		2
Fair value - Derivative Liabilities		2
Notional amount	$ 5	$ 34