Securities-Amortized Cost, Gross Unrealized Gains and Losses and Fair Value of Securities (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Gain (Loss) on Investments [Line Items]
Fair value	$ 99,308	$ 98,752
Securities available-for-sale
Gain (Loss) on Investments [Line Items]
Fair value	80,216	79,309
Government Sponsored and Guaranteed Entities, and Sovereign Debt Securities | Securities available-for-sale
Gain (Loss) on Investments [Line Items]
Fair value	$ 12,200	$ 11,400