Notional Amounts and Fair Values for All Derivative Instruments Included in the Consolidated Balance Sheets (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Derivatives, Fair Value
Fair value - Derivative Assets	$ 1,848	$ 1,972
Fair value - Derivative Liabilities	866	915
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges
Derivatives, Fair Value
Fair value - Derivative Assets	550	640
Fair value - Derivative Liabilities	1	1
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Fair Value Hedging
Derivatives, Fair Value
Fair value - Derivative Assets	492	558
Fair value - Derivative Liabilities	1
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Fair Value Hedging | Interest Rate Swap | Long-Term Debt
Derivatives, Fair Value
Notional amount	3,880	2,880
Fair value - Derivative Assets	492	558
Fair value - Derivative Liabilities	1
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Cash Flow Hedging
Derivatives, Fair Value
Fair value - Derivative Assets	58	82
Fair value - Derivative Liabilities		1
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Cash Flow Hedging | Interest Rate Swap | Long-Term Debt
Derivatives, Fair Value
Notional amount		250
Fair value - Derivative Liabilities		1
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Cash Flow Hedging | Interest Rate Swap | Commercial and Industrial Loans
Derivatives, Fair Value
Notional amount	1,000	1,000
Fair value - Derivative Assets	55	60
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Cash Flow Hedging | Interest Rate Floor | Commercial and Industrial Loans
Derivatives, Fair Value
Notional amount	1,500	1,500
Fair value - Derivative Assets	3	22
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Cash Flow Hedging | Interest Rate Cap | Long-Term Debt
Derivatives, Fair Value
Notional amount		500
Nondesignated
Derivatives, Fair Value
Fair value - Derivative Assets	1,298	1,332
Fair value - Derivative Liabilities	865	914
Nondesignated | Risk Management and Other Business Purposes
Derivatives, Fair Value
Fair value - Derivative Assets	418	398
Fair value - Derivative Liabilities	59	47
Nondesignated | Risk Management and Other Business Purposes | Interest Rate Contract | Servicing Rights
Derivatives, Fair Value
Notional amount	5,952	10,177
Fair value - Derivative Assets	199	219
Nondesignated | Risk Management and Other Business Purposes | Forward Contracts | Assets Held-for-sale
Derivatives, Fair Value
Notional amount	7,752	5,322
Fair value - Derivative Assets	8	2
Fair value - Derivative Liabilities	22	14
Nondesignated | Risk Management and Other Business Purposes | Warrant
Derivatives, Fair Value
Notional amount	484	416
Fair value - Derivative Assets	211	177
Nondesignated | Risk Management and Other Business Purposes | Swap
Derivatives, Fair Value
Notional amount	722	644
Fair value - Derivative Liabilities	37	33
Nondesignated | Customer Accommodation
Derivatives, Fair Value
Fair value - Derivative Assets	880	934
Fair value - Derivative Liabilities	806	867
Nondesignated | Customer Accommodation | Interest Rate Contract
Derivatives, Fair Value
Notional amount	26,597	27,354
Fair value - Derivative Assets	522	586
Fair value - Derivative Liabilities	537	602
Nondesignated | Customer Accommodation | Foreign Exchange Contract
Derivatives, Fair Value
Notional amount	17,476	17,297
Fair value - Derivative Assets	233	201
Fair value - Derivative Liabilities	198	183
Nondesignated | Customer Accommodation | Interest Rate Lock Commitments
Derivatives, Fair Value
Notional amount	4,351	4,894
Fair value - Derivative Assets	51	60
Fair value - Derivative Liabilities	1
Nondesignated | Customer Accommodation | Commodity Contract
Derivatives, Fair Value
Notional amount	3,043	3,084
Fair value - Derivative Assets	74	87
Fair value - Derivative Liabilities	70	82
Nondesignated | Customer Accommodation | Derivative | Certificates of Deposit
Derivatives, Fair Value
Notional amount		$ 5