Fair Value Of Financial Instruments (Details) (USD $)	Jun. 30, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes, Loans and Financing Receivable, Net	$ 22,945,000,000	$ 10,998,000,000
Restricted Cash and Investments	1,426,000,000	744,000,000
Restricted Cash and Cash Equivalents	1,397,000	744,000
Restricted Cash - Derivative Collateral	14,000,000	4,000,000
Interest Rate Swap Agreements - Assets	7,000,000
Interest Rate Cap Agreements Purchased	7,000,000
Investment Foreign Currency, Contract, Amount Purchased	17,000,000
Interest Rate Swap Agreements - Liabilities	20,000,000
Interest Rate Cap Agreements - Sold	7,000,000
Investment Foreign Currency, Contract, Amount Sold	3,000,000
Secured Debt	17,548,000,000	9,378,000,000
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	1,757,000,000	1,289,000,000
Notes, Loans and Financing Receivable, Net	22,945,000,000	10,998,000,000
Restricted Cash and Investments	1,398,000,000	729,000,000
Restricted Cash and Cash Equivalents	28,000,000	15,000,000
Restricted Cash - Derivative Collateral	32,000,000	24,000,000
Interest Rate Swap Agreements - Assets	7,000,000
Interest Rate Cap Agreements Purchased	7,000,000
Investment Foreign Currency, Contract, Amount Purchased	17,000,000
Interest Rate Swap Agreements - Liabilities	20,000,000
Interest Rate Cap Agreements - Sold	7,000,000
Investment Foreign Currency, Contract, Amount Sold	3,000,000
Secured Debt	17,548,000,000	9,378,000,000
Senior Notes	5,238,000,000	1,500,000,000
Portion at Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	1,757,000,000	1,289,000,000
Notes, Loans and Financing Receivable, Net	23,085,000,000	11,313,000,000
Restricted Cash and Investments	1,398,000,000	729,000,000
Restricted Cash and Cash Equivalents	28,000,000	15,000,000
Restricted Cash - Derivative Collateral	32,000,000	24,000,000
Interest Rate Swap Agreements - Assets	7,000,000
Interest Rate Cap Agreements Purchased	7,000,000
Investment Foreign Currency, Contract, Amount Purchased	17,000,000
Interest Rate Swap Agreements - Liabilities	20,000,000
Interest Rate Cap Agreements - Sold	7,000,000
Investment Foreign Currency, Contract, Amount Sold	3,000,000
Secured Debt	17,605,000,000	9,526,000,000
Senior Notes	5,232,000,000	1,620,000,000
Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest Rate Cap Agreements Purchased	7,000,000
Investment Foreign Currency, Contract, Amount Purchased	17,000,000
Interest Rate Cap Agreements - Sold	7,000,000
Investment Foreign Currency, Contract, Amount Sold	3,000,000
Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest Rate Swap Agreements - Assets	7,000,000
Interest Rate Swap Agreements - Liabilities	$ 20,000,000