Notional Amounts and Fair Values for All Derivative Instruments Included in the Consolidated Balance Sheets (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Derivatives, Fair Value
Fair value - Derivative Assets	$ 1,818	$ 1,972
Fair value - Derivative Liabilities	871	915
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges
Derivatives, Fair Value
Fair value - Derivative Assets	426	640
Fair value - Derivative Liabilities	17	1
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Fair Value Hedging
Derivatives, Fair Value
Fair value - Derivative Assets	381	558
Fair value - Derivative Liabilities	17
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	381	558
Fair value - Derivative Liabilities	17
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	1,392	1,332
Fair value - Derivative Liabilities	854	914
Nondesignated | Risk Management and Other Business Purposes
Derivatives, Fair Value
Fair value - Derivative Assets	610	398
Fair value - Derivative Liabilities	73	47
Nondesignated | Risk Management and Other Business Purposes | Interest Rate Contract | Servicing Rights
Derivatives, Fair Value
Notional amount	3,017	10,177
Fair value - Derivative Assets	138	219
Fair value - Derivative Liabilities	10
Nondesignated | Risk Management and Other Business Purposes | Forward Contracts | Assets Held-for-sale
Derivatives, Fair Value
Notional amount	7,298	5,322
Fair value - Derivative Assets	185	2
Fair value - Derivative Liabilities	26	14
Nondesignated | Risk Management and Other Business Purposes | Warrant
Derivatives, Fair Value
Notional amount	562	416
Fair value - Derivative Assets	287	177
Nondesignated | Risk Management and Other Business Purposes | Swap
Derivatives, Fair Value
Notional amount	777	644
Fair value - Derivative Liabilities	37	33
Nondesignated | Customer Accommodation
Derivatives, Fair Value
Fair value - Derivative Assets	782	934
Fair value - Derivative Liabilities	781	867
Nondesignated | Customer Accommodation | Interest Rate Contract
Derivatives, Fair Value
Notional amount	29,119	27,354
Fair value - Derivative Assets	420	586
Fair value - Derivative Liabilities	432	602
Nondesignated | Customer Accommodation | Foreign Exchange Contract
Derivatives, Fair Value
Notional amount	19,789	17,297
Fair value - Derivative Assets	257	201
Fair value - Derivative Liabilities	215	183
Nondesignated | Customer Accommodation | Interest Rate Lock Commitments
Derivatives, Fair Value
Notional amount	3,326	4,894
Fair value - Derivative Assets	7	60
Fair value - Derivative Liabilities	35
Nondesignated | Customer Accommodation | Commodity Contract
Derivatives, Fair Value
Notional amount	3,583	3,084
Fair value - Derivative Assets	98	87
Fair value - Derivative Liabilities	99	82
Nondesignated | Customer Accommodation | Derivative | Certificates of Deposit
Derivatives, Fair Value
Notional amount		$ 5