Total Gains and Losses Included in Earnings for Assets and Liabilites Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3) (Detail) (Fair Value, Inputs, Level 3, USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation
Gains and losses included in earnings	$ 3	$ 84
Mortgage Banking Revenue
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation
Gains and losses included in earnings	38	57
Other Noninterest Income
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation
Gains and losses included in earnings	$ (35)	$ 27