Notional Amounts and Fair Values for All Derivative Instruments Included in the Consolidated Balance Sheets (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Derivatives, Fair Value
Fair value - Derivative Assets	$ 1,586	$ 1,972
Fair value - Derivative Liabilities	807	915
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges
Derivatives, Fair Value
Fair value - Derivative Assets	390	640
Fair value - Derivative Liabilities	11	1
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Fair Value Hedging
Derivatives, Fair Value
Fair value - Derivative Assets	345	558
Fair value - Derivative Liabilities	11
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Fair Value Hedging | Interest Rate Swap | Long-Term Debt
Derivatives, Fair Value
Notional amount	3,205	2,880
Fair value - Derivative Assets	345	558
Fair value - Derivative Liabilities	11
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Cash Flow Hedging
Derivatives, Fair Value
Fair value - Derivative Assets	45	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	45	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
Fair value - Derivative Assets		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	1,196	1,332
Fair value - Derivative Liabilities	796	914
Nondesignated | Risk Management and Other Business Purposes
Derivatives, Fair Value
Fair value - Derivative Assets	452	398
Fair value - Derivative Liabilities	87	47
Nondesignated | Risk Management and Other Business Purposes | Interest Rate Contract | Servicing Rights
Derivatives, Fair Value
Notional amount	2,992	10,177
Fair value - Derivative Assets	147	219
Fair value - Derivative Liabilities	8
Nondesignated | Risk Management and Other Business Purposes | Forward Contracts | Assets Held-for-sale
Derivatives, Fair Value
Notional amount	4,068	5,322
Fair value - Derivative Assets	12	2
Fair value - Derivative Liabilities	44	14
Nondesignated | Risk Management and Other Business Purposes | Warrant
Derivatives, Fair Value
Notional amount	569	416
Fair value - Derivative Assets	293	177
Nondesignated | Risk Management and Other Business Purposes | Swap
Derivatives, Fair Value
Notional amount	812	644
Fair value - Derivative Liabilities	35	33
Nondesignated | Customer Accommodation
Derivatives, Fair Value
Fair value - Derivative Assets	744	934
Fair value - Derivative Liabilities	709	867
Nondesignated | Customer Accommodation | Interest Rate Contract
Derivatives, Fair Value
Notional amount	29,128	27,354
Fair value - Derivative Assets	399	586
Fair value - Derivative Liabilities	412	602
Nondesignated | Customer Accommodation | Foreign Exchange Contract
Derivatives, Fair Value
Notional amount	18,299	17,297
Fair value - Derivative Assets	237	201
Fair value - Derivative Liabilities	214	183
Nondesignated | Customer Accommodation | Interest Rate Lock Commitments
Derivatives, Fair Value
Notional amount	1,433	4,894
Fair value - Derivative Assets	25	60
Fair value - Derivative Liabilities	1
Nondesignated | Customer Accommodation | Commodity Contract
Derivatives, Fair Value
Notional amount	3,330	3,084
Fair value - Derivative Assets	83	87
Fair value - Derivative Liabilities	82	82
Nondesignated | Customer Accommodation | Derivative | Certificates of Deposit
Derivatives, Fair Value
Notional amount		$ 5