Changes in the Servicing Assets (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Servicing Assets at Fair Value
Carrying amount before valuation allowance as of the beginning of the period	$ 1,204	$ 1,392
Servicing rights that result from the transfer of residential mortgage loans	12	13
Amortization	(27)	(34)
Carrying amount before valuation allowance	1,189	1,371
Valuation allowance for servicing rights:
Beginning balance	(419)	(534)
(Provision for) recovery of MSR impairment	(85)	(48)
Ending balance	(504)	(582)
Carrying amount as of the end of the period	$ 685	$ 789	$ 785