Notional Amounts and Fair Values for All Derivative Instruments Included in the Consolidated Balance Sheets (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	$ 2,236	$ 2,356	$ 2,600
Fair value - Derivative Liabilities	1,072	1,344	1,505
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	713	812	851
Fair value - Derivative Liabilities	2	5	7
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Fair Value Hedging
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	606	662	679
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Fair Value Hedging | Interest Rate Swap | Long-Term Debt
Derivatives, Fair Value [Line Items]
Notional amount	2,880	4,080	4,080
Fair value - Derivative Assets	606	662	679
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Cash Flow Hedging
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	107	150	172
Fair value - Derivative Liabilities	2	5	7
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Cash Flow Hedging | Interest Rate Swap | Long-Term Debt
Derivatives, Fair Value [Line Items]
Notional amount	250	250	250
Fair value - Derivative Liabilities	2	5	7
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]
Notional amount	1,000	1,500	1,500
Fair value - Derivative Assets	65	59	60
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]
Notional amount	1,500	1,500	1,500
Fair value - Derivative Assets	42	91	112
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	500
Nondesignated
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	1,523	1,544	1,749
Fair value - Derivative Liabilities	1,070	1,339	1,498
Nondesignated | Risk Management and Other Business Purposes
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	465	307	311
Fair value - Derivative Liabilities	118	136	104
Nondesignated | Risk Management and Other Business Purposes | Interest Rate Swap | Long-Term Debt
Derivatives, Fair Value [Line Items]
Notional amount		311	360
Fair value - Derivative Assets		1	1
Fair value - Derivative Liabilities		3	3
Nondesignated | Risk Management and Other Business Purposes | Interest Rate Contract | Mortgage Servicing Rights
Derivatives, Fair Value [Line Items]
Notional amount	9,327	3,077	3,577
Fair value - Derivative Assets	258	187	193
Fair value - Derivative Liabilities	5		2
Nondesignated | Risk Management and Other Business Purposes | Forward Contracts | Assets Held-for-sale
Derivatives, Fair Value [Line Items]
Notional amount	8,749	5,705	5,062
Fair value - Derivative Assets	10	8	4
Fair value - Derivative Liabilities	92	54	59
Nondesignated | Risk Management and Other Business Purposes | Foreign Exchange Contract
Derivatives, Fair Value [Line Items]
Notional amount			1,696
Fair value - Derivative Assets			12
Fair value - Derivative Liabilities			12
Nondesignated | Risk Management and Other Business Purposes | Put Option
Derivatives, Fair Value [Line Items]
Notional amount		978	901
Fair value - Derivative Liabilities		1	1
Nondesignated | Risk Management and Other Business Purposes | Warrant
Derivatives, Fair Value [Line Items]
Notional amount	439	223	205
Fair value - Derivative Assets	197	111	101
Nondesignated | Risk Management and Other Business Purposes | Swap
Derivatives, Fair Value [Line Items]
Notional amount	571	436	423
Fair value - Derivative Liabilities	21	78	27
Nondesignated | Customer Accommodation [Member]
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	1,058	1,237	1,438
Fair value - Derivative Liabilities	952	1,203	1,394
Nondesignated | Customer Accommodation [Member] | Interest Rate Contract
Derivatives, Fair Value [Line Items]
Notional amount	27,112	30,000	29,433
Fair value - Derivative Assets	640	774	827
Fair value - Derivative Liabilities	658	795	851
Nondesignated | Customer Accommodation [Member] | Foreign Exchange Contract
Derivatives, Fair Value [Line Items]
Notional amount	18,809	17,909	19,243
Fair value - Derivative Assets	216	294	459
Fair value - Derivative Liabilities	198	275	435
Nondesignated | Customer Accommodation [Member] | Interest Rate Lock Commitments
Derivatives, Fair Value [Line Items]
Notional amount	5,154	3,835	4,772
Fair value - Derivative Assets	102	33	38
Fair value - Derivative Liabilities		1	1
Nondesignated | Customer Accommodation [Member] | Commodity Contract
Derivatives, Fair Value [Line Items]
Notional amount	2,860	2,074	2,102
Fair value - Derivative Assets	99	134	112
Fair value - Derivative Liabilities	95	130	105
Nondesignated | Customer Accommodation [Member] | Derivative | Certificates of Deposit
Derivatives, Fair Value [Line Items]
Notional amount	13	34	34
Fair value - Derivative Assets	1	2	2
Fair value - Derivative Liabilities	$ 1	$ 2	$ 2