Fair Value Measurement - Schedule of Earnings Related to Assets Measured at Fair Value on Nonrecurring Basis (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Assets:
Loans held for investment	$ (38)	$ (71)
Loans held for sale	0	0
Other assets	(5)	(4)
Total	$ (43)	$ (75)