Variable Interest Entities - Summary of Assets and Liabilities of Consolidated Secured Financing VIEs (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Variable Interest Entity [Line Items]
Cash	$ 124	$ 157
Credit loss reserves	(311)	(2,217)	$ (3,273)	$ (4,607)
Total receivables, net	8,987	21,242
Long-term debt	9,510	16,427
Variable Interest Entity [Member]
Variable Interest Entity [Line Items]
Cash	0	2
Real estate secured receivables	1,654	2,999
Accrued interest income and other	76	133
Credit loss reserves	(94)	(337)
Total receivables, net	1,636	2,795
Total, Consolidated Assets	1,636	2,797
Other liabilities	(22)	(35)
Long-term debt	879	1,489
Total, Consolidated Liabilities	$ 857	$ 1,454