Debt (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Long-term debt
Current maturities of long-term debt	$ 32,208	$ 24,524
Total long-term debt, less current maturities	238,885	276,825
Nonrecourse [Member]
Long-term debt
Total long-term debt	954	15,991
Current maturities of long-term debt	157	2,841
Total long-term debt, less current maturities	797	13,150
Note Payable, 5.96%, payable $218 monthly plus interest, due 2013 [Member] | Nonrecourse [Member]
Long-term debt
Total long-term debt	0	14,550
Note Payable, 6.37%, payable $24 monthly, due 2014 [Member] | Nonrecourse [Member]
Long-term debt
Total long-term debt	954	1,405
Note Payable, 7.06%, payable $2 monthly, due 2011 [Member] | Nonrecourse [Member]
Long-term debt
Total long-term debt	$ 0	$ 36