Debt Short Term and Long Term Debt (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Short Term and Long Term Debt [Line Items]
Secured debt	$ 22,932	$ 22,073
Unsecured debt	10,842	6,973
Revolving Credit Facility [Member]
Short Term and Long Term Debt [Line Items]
Secured debt	6,433	9,000
Unsecured debt	2,217	2,370
Securitization Notes Payable [Member]
Short Term and Long Term Debt [Line Items]
Secured debt	16,499	13,073
Senior Notes [Member]
Short Term and Long Term Debt [Line Items]
Unsecured debt	7,858	4,000
Other Unsecured Debt [Member]
Short Term and Long Term Debt [Line Items]
Unsecured debt	767	603
North America Segment [Member]
Short Term and Long Term Debt [Line Items]
Secured debt	12,874	12,479
Unsecured debt	7,858	4,000
North America Segment [Member] | Revolving Credit Facility [Member]
Short Term and Long Term Debt [Line Items]
Secured debt	697	1,678
Unsecured debt	0	0
North America Segment [Member] | Securitization Notes Payable [Member]
Short Term and Long Term Debt [Line Items]
Secured debt	12,177	10,801
North America Segment [Member] | Senior Notes [Member]
Short Term and Long Term Debt [Line Items]
Unsecured debt	7,858	4,000
International Segment [Member]
Short Term and Long Term Debt [Line Items]
Secured debt	10,058	9,594
Unsecured debt	2,984	2,973
International Segment [Member] | Revolving Credit Facility [Member]
Short Term and Long Term Debt [Line Items]
Secured debt	5,736	7,322
Unsecured debt	2,217	2,370
International Segment [Member] | Securitization Notes Payable [Member]
Short Term and Long Term Debt [Line Items]
Secured debt	4,322	2,272
International Segment [Member] | Senior Notes [Member]
Short Term and Long Term Debt [Line Items]
Unsecured debt	0	0
International Segment [Member] | Other Unsecured Debt [Member]
Short Term and Long Term Debt [Line Items]
Unsecured debt	$ 767	$ 603