Available-for-Sale and Held-to-Maturity Securities (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Investment Holdings [Line Items]
FHLB, restricted stock holdings	$ 402		$ 497
Federal Reserve Bank, restricted stock holdings	349		347
Available for sale and other securities	18,597	[1]	15,207	[1]
Interest-Only-Strip
Investment Holdings [Line Items]
Available for sale and other securities	$ 262		$ 408

[1] Amortized cost of $18,409 and $ 14,571 at December 31, 2013 and 2012, respectively.