INVESTMENTS - Net Effect on Shareholders' Equity of Unrealized Gains and Losses from Investment Securities (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Investments [Abstract]
Unrealized gains (losses) on securities available for sale	$ 3,491	$ 1,761
Unamortized unrealized gains on securities transferred to held to maturity	24	34
Deferred income taxes	(1,255)	(652)
Shareholders' equity, unrealized gains (losses) on investment securities	$ 2,260	$ 1,143