Variable Interest Entities - Assets and Liabilities of Consolidated VIE's (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Restricted cash	$ 2,302
Finance receivables, net of fees	42,172	$ 33,475
Lease related assets	42,882	34,342	$ 20,100
Securitization and Credit Facility VIE [Member]
Variable Interest Entity [Line Items]
Restricted cash	2,267	1,780
Finance receivables, net of fees	28,364	24,644
Lease related assets	22,222	19,341
Secured debt	$ 39,328	$ 34,185