Debt (Details) (USD $)	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010	Feb. 26, 2010
Long-term debt
Current maturities of long -term debt, Total	$ 45,432,000	$ 24,524,000	$ 23,986,000
Long-term debt, less current maturities, Total	260,645,000	276,825,000	281,740,000
Debt (Textuals) [Abstract]
Total borrowing capacity under lines of credit	1,100,000,000
Short-term line of credit facility amount outstanding	880,000,000
Senior Guaranteed Notes				92,000,000
Series A due in 2011				17,000,000
Series A-1- Due on 2012				25,000,000
Series A-2- Due on 2013				25,000,000
Series A-3- Due on 2014				25,000,000
Nonrecourse [Member]
Long-term debt
Current maturities of long -term debt, Total	2,827,000	2,841,000	3,076,000
Long-term debt, less current maturities, Total	11,690,000	13,150,000	14,579,000
Recourse [Member]
Long-term debt
Current maturities of long -term debt, Total	42,605,000	21,683,000	20,910,000
Long-term debt, less current maturities, Total	$ 248,955,000	$ 263,675,000	$ 267,161,000