Changes in the Servicing Assets (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Servicing Assets at Fair Value
Carrying amount as of the beginning of the period	$ 1,440	$ 1,358
Servicing Obligations From Transfers	23	73
Servicing Asset At Amortized Value Amortization	(23)	(53)
Carrying amount before valuation allowance	1,440	1,384
Valuation allowance for servicing assets:
Beginning balance	(469)	(661)
Servicing impairment	4	49
Ending balance	(465)	(612)
Carrying amount as of the end of the period	975	772
Automobile Loan Securitizations
Servicing Assets at Fair Value
Servicing Obligations From Transfers		$ 6