Derivatives Derivatives (Diesel Crack Spread Swaps) (Details) - Fuel Product - Not Designated as Hedging Instrument - Diesel Crack Spread Swaps	Dec. 31, 2019 bbl $ / bbl	Dec. 31, 2018 bbl $ / bbl
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	1,615,500	1,825,000
Average Swap ($/Bbl) | $ / bbl	22.00	25.58
First Quarter 2020 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	500,500
Barrels per Day Sold	5,500
Average Swap ($/Bbl) | $ / bbl	22.15
Second Quarter 2020 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	379,000
Barrels per Day Sold	4,165
Average Swap ($/Bbl) | $ / bbl	21.68
Third Quarter 2020 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	368,000
Barrels per Day Sold	4,000
Average Swap ($/Bbl) | $ / bbl	22.23
Fourth Quarter 2020 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	368,000
Barrels per Day Sold	4,000
Average Swap ($/Bbl) | $ / bbl	21.91
First Quarter 2019 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount		450,000
Barrels per Day Sold		5,000
Average Swap ($/Bbl) | $ / bbl		25.58
Second Quarter 2019 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount		455,000
Barrels per Day Sold		5,000
Average Swap ($/Bbl) | $ / bbl		25.58
Third Quarter 2019 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount		460,000
Barrels per Day Sold		5,000
Average Swap ($/Bbl) | $ / bbl		25.58
Fourth Quarter 2019 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount		460,000
Barrels per Day Sold		5,000
Average Swap ($/Bbl) | $ / bbl		25.58