Securities-Amortized Cost, Gross Unrealized Gains and Losses and Fair Value of Securities (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Gain (Loss) on Investments [Line Items]
Fair value	$ 115,726		$ 98,752
Securities available-for-sale
Gain (Loss) on Investments [Line Items]
Fair value	95,559	[1]	79,309	[2]
Government Sponsored and Guaranteed Entities, and Sovereign Debt Securities | Securities available-for-sale
Gain (Loss) on Investments [Line Items]
Fair value	$ 15,700		$ 11,400

[1] Includes gross unrealized gains of $64 million and gross unrealized losses of $296 million recorded in accumulated other comprehensive income primarily related to Agency RMBS that were transferred from available-for-sale to held-to-maturity in 2013. The unrealized gains and losses will be amortized into net interest revenue over the estimated lives of the securities.

[2] Includes gross unrealized gains of $74 million and gross unrealized losses of $343 million recorded in accumulated other comprehensive income primarily related to Agency RMBS that were transferred from available-for-sale to held-to-maturity in 2013. The unrealized gains and losses will be amortized into net interest revenue over the estimated lives of the securities.