Corporate Debt (Schedule Of Corporate Debt) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Long-term Debt, Total	$ 380,934,000	$ 383,992,000
Stated interest rate	6.70%
Long-term Debt	380,934,000	383,992,000
Senior notes 6.70%, due 2022 [Member]
Debt Instrument [Line Items]
Long-term Debt, Total	175,000,000	175,000,000
Stated interest rate	6.70%	6.70%
Debt instrument, maturity date	Jan. 01, 2022
Redemption price, percentage of principal amount	100.00%
Long-term Debt	175,000,000	175,000,000
Senior notes 5.375%, due 2022 [Member]
Debt Instrument [Line Items]
Long-term Debt, Total	150,000,000	150,000,000
Due date	December 2022
Stated interest rate	5.375%	5.375%
Redemption price, percentage of principal amount	100.00%
Long-term Debt	150,000,000	150,000,000
Non-recourse debt, 6.75%, due 2016 [Member]
Debt Instrument [Line Items]
Long-term Debt, Total	55,934,000	58,992,000
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	55,934,000	58,992,000
Non Recourse Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Total	55,934,000
Long-term Debt	$ 55,934,000