Debt (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 07, 2011
Debt Instrument [Line Items]
Borrowings under short-term line of credit	$ 24,219	$ 71,500	$ 90,000
Long-term debt
Total current maturities of long-term debt	15,145	32,208
Total long-term debt, less current maturities	427,243	238,885
Nonrecourse
Debt Instrument [Line Items]
Borrowings under short-term line of credit	4,219	0
Long-term debt
Total current maturities of long-term debt	2,496	157
Total long-term debt, less current maturities	20,067	797
Recourse
Debt Instrument [Line Items]
Borrowings under short-term line of credit	20,000	71,500
Long-term debt
Total current maturities of long-term debt	12,649	32,051
Total long-term debt, less current maturities	$ 407,176	$ 238,088