INVESTMENTS - Net Effect on Shareholders' Equity of Unrealized Gains and Losses from Investment Securities (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Investments [Abstract]
Unrealized gains (losses) on securities available for sale	$ 3,932	$ 1,761
Unamortized unrealized gains on securities transferred to held to maturity	20	34
Deferred income taxes	(1,382)	(652)
Shareholders' equity, unrealized gains (losses) on investment securities	$ 2,570	$ 1,143