Mortgage Loan Repurchase Losses (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
Reserve for mortgage loan repurchase losses
Balance at beginning of period	$ 77	$ 363	$ 78	$ 632
Repurchase provision	2	73	12	102
Charge-offs	(2)	(155)	(13)	(453)
Balance at end of period	$ 77	$ 281	$ 77	$ 281