Capital and Financing Transactions, Interest Rate Swaps (Details) (USD $)	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Derivative [Line Items]
Notional amount	$ 125,000,000
Reference rate (in hundredths)	LIBOR
Rate at which reference rate is fixed (in hundredths)	0.70%
Accounts Payable and Other Liabilities [Member]
Derivative [Line Items]
Fair market value liability	(15,348,000,000)	(13,102,000,000)
Swap 1 [Member] | Accounts Payable and Other Liabilities [Member]
Derivative [Line Items]
Notional amount	23,500,000
Reference rate (in hundredths)	1-month LIBOR
Maturity date	Dec. 01, 2014
Fixed rate (in hundredths)	5.80%
Fair market value liability	0	(2,533,000,000)
Swap 2 [Member] | Accounts Payable and Other Liabilities [Member]
Derivative [Line Items]
Notional amount	12,088,000
Reference rate (in hundredths)	1-month LIBOR
Maturity date	Nov. 18, 2014
Fixed rate (in hundredths)	4.10%
Fair market value liability	(639,000,000)	(578,000,000)
Swap 3 [Member] | Accounts Payable and Other Liabilities [Member]
Derivative [Line Items]
Notional amount	50,000,000
Reference rate (in hundredths)	1-month LIBOR
Maturity date	Sep. 28, 2017
Fixed rate (in hundredths)	2.20%
Fair market value liability	(61,000,000)	0
Swap 4 [Member] | Accounts Payable and Other Liabilities [Member]
Derivative [Line Items]
Notional amount	75,000,000
Reference rate (in hundredths)	1-month LIBOR
Maturity date	Sep. 28, 2017
Fixed rate (in hundredths)	2.20%
Fair market value liability	(91,000,000)	0
Swap 5 [Member] | Accounts Payable and Other Liabilities [Member]
Derivative [Line Items]
Notional amount	33,875,000
Reference rate (in hundredths)	1-month LIBOR
Maturity date	Nov. 18, 2017
Fixed rate (in hundredths)	4.70%
Fair market value liability	(3,498,000,000)	(2,699,000,000)
Swap 6 [Member] | Accounts Payable and Other Liabilities [Member]
Derivative [Line Items]
Notional amount	22,000,000
Reference rate (in hundredths)	1-month LIBOR
Maturity date	Jan. 25, 2018
Fixed rate (in hundredths)	4.50%
Fair market value liability	(2,029,000,000)	(1,422,000,000)
Swap 7 [Member] | Accounts Payable and Other Liabilities [Member]
Derivative [Line Items]
Notional amount	48,750,000
Reference rate (in hundredths)	1-month LIBOR
Maturity date	Jan. 25, 2018
Fixed rate (in hundredths)	5.00%
Fair market value liability	(1,688,000,000)	0
Swap 8 [Member] | Accounts Payable and Other Liabilities [Member]
Derivative [Line Items]
Notional amount	9,250,000
Reference rate (in hundredths)	1-month LIBOR
Maturity date	Sep. 30, 2018
Fixed rate (in hundredths)	5.20%
Fair market value liability	(1,279,000,000)	(1,039,000,000)
Swap 9 [Member] | Accounts Payable and Other Liabilities [Member]
Derivative [Line Items]
Notional amount	22,500,000
Reference rate (in hundredths)	1-month LIBOR
Maturity date	Oct. 08, 2018
Fixed rate (in hundredths)	5.40%
Fair market value liability	(3,291,000,000)	(2,723,000,000)
Swap 10 [Member] | Accounts Payable and Other Liabilities [Member]
Derivative [Line Items]
Notional amount	22,100,000
Reference rate (in hundredths)	1-month LIBOR
Maturity date	Nov. 18, 2018
Fixed rate (in hundredths)	5.00%
Fair market value liability	$ (2,772,000,000)	$ (2,108,000,000)