Variable Interest Entities - Summary of Assets and Liabilities of Consolidated Secured Financing VIEs (Detail) - USD ($) $ in Millions	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Credit loss reserves	$ (254)	$ (272)	$ (311)	$ (408)	$ (2,110)	$ (2,217)
Total receivables, net	8,038		8,987
Long-term debt	5,229		9,510
Variable Interest Entity [Member]
Variable Interest Entity [Line Items]
Real estate secured receivables	1,260		1,654
Accrued interest income and other	54		76
Credit loss reserves	(68)		(94)
Total receivables, net	1,246		1,636
Total, Consolidated Assets	1,246		1,636
Other liabilities	(19)		(22)
Long-term debt	644		879
Total, Consolidated Liabilities	$ 625		$ 857