Fair Value of Financial Instruments - Schedule of Earnings Related to Assets Measured at Fair Value on Nonrecurring Basis (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Assets
Loans held for investment	$ (19)	$ (27)
Loans held for sale	0	0
Other assets	(6)	(16)
Total	$ (25)	$ (43)