Mortgage Loan Repurchase Losses (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Reserve for mortgage loan repurchase losses
Balance at beginning of period	$ 78	$ 632
Repurchase provision	5	14
Charge-offs	0	(133)
Balance at end of period	$ 83	$ 513