INVESTMENTS - Net Effect on Shareholders' Equity of Unrealized Gains and Losses from Investment Securities (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Investments [Abstract]
Unrealized gains (losses) on securities available for sale	$ 3,003	$ 3,932
Unamortized unrealized gains on securities transferred to held to maturity	17	20
Deferred income taxes	(1,039)	(1,382)
Shareholders' equity, unrealized gains (losses) on investment securities	$ 1,981	$ 2,570