Restricted Cash (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash and Cash Equivalents	$ 2,101	$ 1,958
Securitization Notes Payable [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash and Cash Equivalents	1,299	1,098
Revolving Credit Facility [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash and Cash Equivalents	377	477
Other Liabilities [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash and Cash Equivalents	425	383
North America Segment [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash and Cash Equivalents	1,109	978
North America Segment [Member] | Securitization Notes Payable [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash and Cash Equivalents	1,005	890
North America Segment [Member] | Revolving Credit Facility [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash and Cash Equivalents	65	62
North America Segment [Member] | Other Liabilities [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash and Cash Equivalents	39	26
International Segment [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash and Cash Equivalents	992	980
International Segment [Member] | Securitization Notes Payable [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash and Cash Equivalents	294	208
International Segment [Member] | Revolving Credit Facility [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash and Cash Equivalents	312	415
International Segment [Member] | Other Liabilities [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash and Cash Equivalents	$ 386	$ 357