Derivatives Derivatives (Gasoline Crack Spread Swaps) (Details) - Fuel Product - Not Designated as Hedging Instrument - Gasoline Crack Spread Swaps Sold [Member]	Dec. 31, 2019 bbl $ / bbl	Dec. 31, 2018 bbl
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	1,706,500	0
Average Swap ($/Bbl) | $ / bbl	13.38
First Quarter 2020 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	591,500
Barrels per Day Sold	6,500
Average Swap ($/Bbl) | $ / bbl	12.54
Second Quarter 2020 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	379,000
Barrels per Day Sold	4,165
Average Swap ($/Bbl) | $ / bbl	16.41
Third Quarter 2020 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	368,000
Barrels per Day Sold	4,000
Average Swap ($/Bbl) | $ / bbl	15.24
Fourth Quarter 2020 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	368,000
Barrels per Day Sold	4,000
Average Swap ($/Bbl) | $ / bbl	9.77