Variable Interest Entities - Assets and Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Assets	$ 77,603	$ 65,904
Liabilities	69,130	57,852
Finance receivables, net	39,430	36,781
Secured debt (Note 7; Note 8 VIEs)	34,338	30,689
Other VIE [Member]
Variable Interest Entity [Line Items]
Assets	4,700	3,652
Liabilities	3,962	2,941
Finance receivables, net	3,600	3,200
Secured debt (Note 7; Note 8 VIEs)	$ 2,900	$ 2,600