Derivatives (Schedule of Outstanding Derivatives Entered Into to Hedge Inventory or Fixed Price Purchase Commitments) (Details) gal in Thousands, bbl in Thousands, MMBTU in Thousands	9 Months Ended
	Sep. 30, 2019 MMBTU $ / bbl $ / MMBTU $ / gal $ / units bbl gal
Designated as hedges under accounting rules | Sell (Short) Contracts | Future | Crude Oil
Derivative [Line Items]
Contract volumes (bbls/gal) | bbl	49
Weighted average contract price	57.20
Designated as hedges under accounting rules | Buy (Long) Contracts | Future | Crude Oil
Derivative [Line Items]
Contract volumes (bbls/gal) | bbl	0
Weighted average contract price	0
Not qualifying or not designated as hedges under accounting rules | Sell (Short) Contracts | Future | Crude Oil
Derivative [Line Items]
Contract volumes (bbls/gal) | bbl	312
Weighted average contract price	57.68
Not qualifying or not designated as hedges under accounting rules | Sell (Short) Contracts | Future | Natural Gas
Derivative [Line Items]
Contract volume (MMBTU) | MMBTU	92
Weighted average contract price | $ / MMBTU	2.31
Not qualifying or not designated as hedges under accounting rules | Sell (Short) Contracts | Future | NYM NYHBRULSD
Derivative [Line Items]
Contract volumes (bbls/gal) | gal	2
Weighted average contract price	2.01
Not qualifying or not designated as hedges under accounting rules | Sell (Short) Contracts | Future | NYM RBOB
Derivative [Line Items]
Contract volumes (bbls/gal) | gal	6
Weighted average contract price | $ / gal	1.62
Not qualifying or not designated as hedges under accounting rules | Sell (Short) Contracts | Future | Fuel Oil
Derivative [Line Items]
Contract volumes (bbls/gal) | bbl	140
Weighted average contract price	44.15
Not qualifying or not designated as hedges under accounting rules | Sell (Short) Contracts | Swap | Natural Gas
Derivative [Line Items]
Contract volume (MMBTU) | MMBTU	549
Weighted average contract price	0.41
Not qualifying or not designated as hedges under accounting rules | Sell (Short) Contracts | Options | Crude Oil
Derivative [Line Items]
Contract volumes (bbls/gal) | bbl	33
Weighted average premium received/paid	1.37
Not qualifying or not designated as hedges under accounting rules | Buy (Long) Contracts | Future | Crude Oil
Derivative [Line Items]
Contract volumes (bbls/gal) | bbl	181
Weighted average contract price	57.63
Not qualifying or not designated as hedges under accounting rules | Buy (Long) Contracts | Future | Natural Gas
Derivative [Line Items]
Contract volume (MMBTU) | MMBTU	591
Weighted average contract price | $ / MMBTU	2.69
Not qualifying or not designated as hedges under accounting rules | Buy (Long) Contracts | Future | NYM NYHBRULSD
Derivative [Line Items]
Contract volumes (bbls/gal) | gal	2
Weighted average contract price	1.99
Not qualifying or not designated as hedges under accounting rules | Buy (Long) Contracts | Future | NYM RBOB
Derivative [Line Items]
Contract volumes (bbls/gal) | gal	6
Weighted average contract price | $ / gal	1.53
Not qualifying or not designated as hedges under accounting rules | Buy (Long) Contracts | Future | Fuel Oil
Derivative [Line Items]
Contract volumes (bbls/gal) | bbl	155
Weighted average contract price	42.49
Not qualifying or not designated as hedges under accounting rules | Buy (Long) Contracts | Swap | Natural Gas
Derivative [Line Items]
Contract volume (MMBTU) | MMBTU	0
Weighted average contract price | $ / units	0
Not qualifying or not designated as hedges under accounting rules | Buy (Long) Contracts | Options | Crude Oil
Derivative [Line Items]
Contract volumes (bbls/gal) | bbl	5
Weighted average premium received/paid	0.27