Derivatives Derivatives - Schedule of positions (Diesel - MEH Crack Spread Swaps) (Details) - Not Designated as Hedging Instrument [Member] - Diesel-MEH crack spread swap [Member] [Domain] - Fuel Product [Member]	Jun. 30, 2020 MMBTU $ / bbl bbl	Dec. 31, 2019 MMBTU
Derivative [Line Items]
Average Swap ($/Bbl) | $ / bbl	9.51
Derivative, Nonmonetary Notional Amount | MMBTU	736,000	0
Third Quarter 2020
Derivative [Line Items]
Barrels per Day Purchased | bbl	4,000
Average Swap ($/Bbl) | $ / bbl	9.51
Derivative, Nonmonetary Notional Amount | MMBTU	368,000
Fourth Quarter 2020
Derivative [Line Items]
Barrels per Day Purchased | bbl	4,000
Average Swap ($/Bbl) | $ / bbl	9.51
Derivative, Nonmonetary Notional Amount | MMBTU	368,000