Notional Amounts and Fair Values for All Derivative Instruments Included in the Consolidated Balance Sheets (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	$ 1,532	$ 1,553
Fair value - Derivative Liabilities	677	754
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	367	332
Fair value - Derivative Liabilities	19	34
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Fair Value Hedging
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	340	292
Fair value - Derivative Liabilities	13	13
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	3,855	3,205
Fair value - Derivative Assets	340	292
Fair value - Derivative Liabilities	13	13
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Cash Flow Hedging
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	27	40
Fair value - Derivative Liabilities	6	21
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Cash Flow Hedging | Interest Rate Swap | Commercial and Industrial Loans
Derivatives, Fair Value [Line Items]
Notional amount	2,700	2,200
Fair value - Derivative Assets	27	40
Fair value - Derivative Liabilities	6	21
Nondesignated
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	1,165	1,221
Fair value - Derivative Liabilities	658	720
Nondesignated | Risk Management and Other Business Purposes
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	504	538
Fair value - Derivative Liabilities	57	63
Nondesignated | Risk Management and Other Business Purposes | Interest Rate Contract | Servicing Rights
Derivatives, Fair Value [Line Items]
Notional amount	4,737	4,092
Fair value - Derivative Assets	145	141
Fair value - Derivative Liabilities	2	14
Nondesignated | Risk Management and Other Business Purposes | Forward Contracts | Assets Held-for-sale
Derivatives, Fair Value [Line Items]
Notional amount	977	1,448
Fair value - Derivative Assets	1	13
Fair value - Derivative Liabilities	2	1
Nondesignated | Risk Management and Other Business Purposes | Warrant
Derivatives, Fair Value [Line Items]
Notional amount	630	664
Fair value - Derivative Assets	358	384
Nondesignated | Risk Management and Other Business Purposes | Swap
Derivatives, Fair Value [Line Items]
Notional amount	907	947
Fair value - Derivative Liabilities	53	48
Nondesignated | Customer Accommodation
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	661	683
Fair value - Derivative Liabilities	601	657
Nondesignated | Customer Accommodation | Interest Rate Contract
Derivatives, Fair Value [Line Items]
Notional amount	28,484	28,112
Fair value - Derivative Assets	255	329
Fair value - Derivative Liabilities	263	339
Nondesignated | Customer Accommodation | Interest Rate Lock Commitments
Derivatives, Fair Value [Line Items]
Notional amount	532	924
Fair value - Derivative Assets	10	12
Fair value - Derivative Liabilities		1
Nondesignated | Customer Accommodation | Commodity Contract
Derivatives, Fair Value [Line Items]
Notional amount	3,511	3,300
Fair value - Derivative Assets	83	66
Fair value - Derivative Liabilities	80	65
Nondesignated | Customer Accommodation | Foreign Exchange Contract
Derivatives, Fair Value [Line Items]
Notional amount	18,405	19,688
Fair value - Derivative Assets	313	276
Fair value - Derivative Liabilities	$ 258	$ 252