Deposits - Maturities of Time Deposits (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Deposits [Abstract]
Total domestic time deposits greater than $100,000	$ 12
Domestic time deposits greater than $100,000 maturing within three months	4
Domestic time deposits greater than $100,000 maturing within three to six months	4
Domestic time deposits greater than $100,000 maturing within six to twelve months	2
Domestic time deposits greater than $100,000 maturing after twelve months	2
Deposits at fair value	$ 7,696	$ 7,255