Corporate Debt (Schedule Of Corporate Debt) (Details) (USD $)				9 Months Ended		9 Months Ended		9 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Senior notes 6.70%, due 2022 [Member]	Dec. 31, 2012 Senior notes 6.70%, due 2022 [Member]	Sep. 30, 2013 Senior notes 5.375%, due 2022 [Member]	Dec. 31, 2012 Senior notes 5.375%, due 2022 [Member]	Sep. 30, 2013 Non-recourse debt, 6.75%, due 2016 [Member]	Dec. 31, 2012 Non-recourse debt, 6.75%, due 2016 [Member]	Sep. 30, 2013 Non Recourse Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Total	$ 357,111,000		$ 383,992,000	$ 175,000,000	$ 175,000,000	$ 150,000,000	$ 150,000,000	$ 32,111,000	$ 58,992,000	$ 32,111,000
Due date						December 2022
Stated interest rate		6.70%		6.70%	6.70%	5.375%	5.375%
Debt instrument, maturity date				Jan. 01, 2022
Redemption price, percentage of principal amount				100.00%		100.00%
Principal								60,000,000
Non recourse debt, percentage of montly lease payments required to be collected								100.00%
Non recourse debt, percentage of montly lease payments required to be allocated to interest								65.00%
Long-term Debt	$ 357,111,000		$ 383,992,000	$ 175,000,000	$ 175,000,000	$ 150,000,000	$ 150,000,000	$ 32,111,000	$ 58,992,000	$ 32,111,000