Changes in the Servicing Assets (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Servicing Assets at Fair Value [Line Items]
Carrying amount before valuation allowance as of the beginning of the period			$ 1,392	$ 1,440
Servicing rights that result from the transfer of residential mortgage or automobile loans			31	44
Amortization	$ (40)	$ (33)	(74)	(56)
Carrying amount before valuation allowance	1,349	1,428	1,349	1,428
Valuation allowance for servicing assets:
Beginning balance			(534)	(469)
(Provision for) recovery of MSR impairment			39	(28)
Ending balance	(495)	(497)	(495)	(497)
Carrying amount as of the end of the period	$ 854	$ 931	$ 854	$ 931