Fair Value Measurement - Schedule of Earnings Related to Assets Measured at Fair Value on Nonrecurring Basis (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Assets:
Loans held for investment	$ (70)	$ (19)
Loans held for sale	0	0
Other assets	(35)	(6)
Total	$ (105)	$ (25)