Derivatives (WCS Crude Oil Basis Swaps) (Details) - Fuel Product - Not Designated as Hedging Instrument - WCS Crude Oil Basis Swaps	Dec. 31, 2019 bbl $ / bbl	Dec. 31, 2018 bbl $ / bbl
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	544,000	1,794,000
Average Swap ($/Bbl) | $ / bbl	(18.92)	(28.19)
First Quarter 2020 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	544,000
Barrels per Day Purchased	5,978
Average Swap ($/Bbl) | $ / bbl	(18.92)
First Quarter 2019 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount		419,000
Barrels per Day Purchased		4,656
Average Swap ($/Bbl) | $ / bbl		(28.10)
Second Quarter 2019 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount		455,000
Barrels per Day Purchased		5,000
Average Swap ($/Bbl) | $ / bbl		(28.22)
Third Quarter 2019 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount		460,000
Barrels per Day Purchased		5,000
Average Swap ($/Bbl) | $ / bbl		(28.22)
Fourth Quarter 2019 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount		460,000
Barrels per Day Purchased		5,000
Average Swap ($/Bbl) | $ / bbl		(28.22)