Impacts of Derivative Financial Instruments on the Consolidated Statements of Income/(Loss) and the Consolidated Statements of Shareholders' Equity (Additional Information) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Interest Income (Expense), Net [Member]
Reclassified in pre-tax gains from AOCI into net interest income	$ 19	$ 26
Not Designated as Hedging Instrument [Member]
Derivative, Gain (Loss) on Derivative, Net	$ 206	$ 105