Fair Value Measurement - Schedule of Earnings Related to Assets Measured at Fair Value on Nonrecurring Basis (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Assets:
Loans held for investment	$ (116)	$ (105)
Loans held for sale	(3)	0
Other assets	(6)	(6)
Total	$ (125)	$ (111)