Variable Interest Entities - Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Assets	$ 94,540	$ 87,765
Liabilities	85,548	79,072
Finance receivables, net	46,910	43,190
Secured debt (Note 7; Note 8 VIEs)	42,579	39,270
Other VIE [Member]
Variable Interest Entity [Line Items]
Assets	4,312	4,251
Liabilities	3,604	3,559
Finance receivables, net	3,600	3,500
Secured debt (Note 7; Note 8 VIEs)	$ 3,000	$ 3,000