Mortgage Loan Repurchase Losses (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reserve for mortgage loan repurchase losses
Balance at beginning of period	$ 632	$ 320	$ 265
Repurchase provision	114	713	502
Charge-offs	(668)	(401)	(447)
Balance at end of period	$ 78	$ 632	$ 320