Derivatives (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Derivative Asset, Notional Amount	$ 14,394,000	$ 19,361,000
Derivative Liability, Notional Amount	24,319,000	23,191,000
Derivative Assets, Fair Value	644,000	1,225,000
Derivative Liabilities, Fair Value	556,000	2,386,000
Derivative, Gain (Loss) on Derivative, Net	631,000	(1,495,000)	$ (1,919,000)
Foreign exchange
Derivative [Line Items]
Derivative Asset, Notional Amount	0	0
Derivative Liability, Notional Amount	10,787,000	10,996,000
Derivative Assets, Fair Value	74,000	0
Derivative Liabilities, Fair Value	44,000	205,000
Derivative, Gain (Loss) on Derivative, Net	235,000	(141,000)	(1,481,000)
Commodity futures
Derivative [Line Items]
Derivative Asset, Notional Amount	14,394,000	19,361,000
Derivative Liability, Notional Amount	4,623,000	3,434,000
Derivative Assets, Fair Value	570,000	486,000
Derivative Liabilities, Fair Value	339,000	2,181,000
Derivative, Gain (Loss) on Derivative, Net	881,000	(2,093,000)	(438,000)
Commodity swap
Derivative [Line Items]
Derivative Asset, Notional Amount	0	0
Derivative Liability, Notional Amount	8,909,000	8,761,000
Derivative Assets, Fair Value	0	739,000
Derivative Liabilities, Fair Value	173,000	0
Derivative, Gain (Loss) on Derivative, Net	$ (485,000)	739,000	$ 0
Due from brokers
Derivative [Line Items]
Trading investment and held as collateral		$ 2,002,000