INVESTMENTS - Net Effect on Shareholders' Equity of Unrealized Gains and Losses from Investment Securities (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Investments [Abstract]
Unrealized gains (losses) on securities available for sale		$ 6,039	$ 9,358
Deferred income taxes		(1,805)	(3,394)
Shareholders' equity, unrealized gains (losses) on investment securities	[1]	$ 4,234	$ 5,964

[1] See Note 1 of the Notes to the Consolidated Financial Statements for the adoption of accounting guidance on January 1, 2018 related to financial instruments.