Debt (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Debt Instrument [Line Items]
Short-term debt	$ 392,450,000	$ 147,031,000	$ 434,304,000
Long-term debt
Current maturities of long-term debt	80,758,000	62,899,000	55,160,000
Total Current Maturities of Long-term Debt	80,758,000	62,899,000	55,160,000
Long-term debt, less current maturities	987,526,000	1,016,248,000	982,025,000
Total Long-term Debt, Less: Current Maturities	987,526,000	1,016,248,000	982,025,000
Nonrecourse
Debt Instrument [Line Items]
Short-term debt	83,791,000	54,029,000	97,304,000
Long-term debt
Current maturities of long-term debt	5,212,000	9,545,000	7,793,000
Long-term debt, less current maturities	658,064,000	685,997,000	804,070,000
Recourse
Debt Instrument [Line Items]
Short-term debt	308,659,000	93,002,000	337,000,000
Long-term debt
Current maturities of long-term debt	75,546,000	53,354,000	47,367,000
Long-term debt, less current maturities	329,462,000	$ 330,251,000	$ 177,955,000
Line of credit
Long-term debt
Credit facility, maximum borrowing capacity	1,684,000,000.0
Total available for borrowings under lines of credit	$ 1,006,400,000