Intangible Assets - Residential MSRs Activity (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Fair value of MSRs:
Beginning balance	$ 158	$ 186	$ 159	$ 227
Changes in fair value due to changes in valuation model inputs or assumptions	(21)	2	(13)	(22)
Reductions related to customer payments	(7)	(6)	(16)	(23)
Ending balance	$ 130	$ 182	$ 130	$ 182