Intangible Assets - Residential MSRs Activity (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Fair value of MSRs:
Beginning balance	$ 140	$ 205	$ 159	$ 227
Changes in fair value due to:
Changes in fair value due to changes in valuation model inputs or assumptions	19	(12)	8	(24)
Reductions related to customer payments	(1)	(7)	(9)	(17)
Ending balance	$ 158	$ 186	$ 158	$ 186