Change in Fair Value of Financial Instruments for which the FVO has been Elected (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income recognized upon the sale of loans	$ 40	$ 1	$ 71	$ 7
Fair Value, Inputs, Level 2 [Member] | Collateralized Loan Obligations [Member]
Fair Value, Option, Credit Risk, Gains (Losses) on Assets	0	1	0	2
Fair Value, Inputs, Level 2 [Member] | Commercial and Corporate Leveraged Loans [Member] | Trading Securities [Member]
Fair Value, Option, Credit Risk, Gains (Losses) on Assets		$ 1		$ 2