Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Debt Instrument [Line Items]
Short-term debt	$ 434,304	$ 205,000	$ 489,000
Long-term debt
Current maturities of long-term debt	55,160	21,589	14,134
Finance lease liability	6,007	0	0
Total Current Maturities of Long-term Debt	55,160	21,589	14,134
Long-term debt, less current maturities	982,025	496,187	438,628
Finance lease liability	23,058	0	0
Total Long-term Debt, Less: Current Maturities	982,025	496,187	438,628
Nonrecourse
Debt Instrument [Line Items]
Short-term debt	97,304	0	0
Long-term debt
Current maturities of long-term debt	7,147	4,842	2,922
Long-term debt, less current maturities	177,233	146,353	72,977
Recourse
Debt Instrument [Line Items]
Short-term debt	337,000	205,000	489,000
Long-term debt
Current maturities of long-term debt	42,006	16,747	11,212
Long-term debt, less current maturities	$ 781,734	$ 349,834	$ 365,651