Derivative Instruments - (Details Textual) lb in Millions, gal in Millions |
12 Months Ended |
|---|---|
|
Dec. 31, 2016
USD ($)
lb
gal
| |
| Derivative Instruments, Gain (Loss) [Line Items] | |
| Heating oil covered under the open commodity derivative contracts (in gallons) | gal | 45.4 |
| Soybean oil covered under the open commodity derivative contracts (in pounds) | lb | 41.0 |
| Net position | $ 2,239,000 |
| Commodity contract derivatives | |
| Derivative Instruments, Gain (Loss) [Line Items] | |
| Collateral associated with commodity-based derivatives | $ 9,366,000 |