Geographic Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Total revenue	$ 2,599	$ 2,478	$ 2,338	$ 2,282	$ 2,291	$ 2,312	$ 2,234	$ 2,159	$ 9,697	$ 8,996	$ 8,182
Income before income taxes									2,086	1,854	1,756
Net finance receivables and net investment in operating leases	121,902				108,433				121,902	108,433	99,913
United States
Segment Reporting Information [Line Items]
Total revenue									7,070	6,377	5,739
Income before income taxes									1,298	1,199	1,160
Net finance receivables and net investment in operating leases	88,237				76,578				88,237	76,578	70,513
Canada
Segment Reporting Information [Line Items]
Total revenue									981	998	909
Income before income taxes									247	148	127
Net finance receivables and net investment in operating leases	10,037				10,449				10,037	10,449	10,085
Europe
Segment Reporting Information [Line Items]
Total revenue									979	1,041	1,132
Income before income taxes									316	332	319
Net finance receivables and net investment in operating leases	18,657				16,708				18,657	16,708	15,674
All Other
Segment Reporting Information [Line Items]
Total revenue									667	580	402
Income before income taxes									225	175	150
Net finance receivables and net investment in operating leases	$ 4,971				$ 4,698				$ 4,971	$ 4,698	$ 3,641