Derivatives (Schedule of Outstanding Derivatives Entered Into to Hedge Inventory or Fixed Price Purchase Commitments) (Details) bbl in Thousands	9 Months Ended
Sep. 30, 2017 bbl $ / bbl
Future \| Sell (Short) Contracts \| Crude Oil \| Designated as Hedging Instrument
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount \| bbl	694
Weighted average contract price per gal \| $ / bbl	48.03
Future \| Sell (Short) Contracts \| Crude Oil \| Not Designated As Hedging Instrument
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount \| bbl	482
Weighted average contract price per gal \| $ / bbl	50.17
Future \| Sell (Short) Contracts \| Diesel Futures [Member] \| Not Designated As Hedging Instrument
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount \| bbl	11
Weighted average contract price per gal \| $ / bbl	1.71
Future \| Sell (Short) Contracts \| RBOB Gas Futures [Member] \| Not Designated As Hedging Instrument
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount \| bbl	0
Weighted average contract price per gal \| $ / bbl	0.00
Future \| Sell (Short) Contracts \| Fuel Oil Futures \| Not Designated As Hedging Instrument
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount \| bbl	175
Weighted average contract price per gal \| $ / bbl	48.10
Future \| Buy (Long) Contracts \| Crude Oil \| Designated as Hedging Instrument
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount \| bbl	0
Weighted average contract price per gal \| $ / bbl	0.00
Future \| Buy (Long) Contracts \| Crude Oil \| Not Designated As Hedging Instrument
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount \| bbl	322
Weighted average contract price per gal \| $ / bbl	50.76
Future \| Buy (Long) Contracts \| Diesel Futures [Member] \| Not Designated As Hedging Instrument
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount \| bbl	11
Weighted average contract price per gal \| $ / bbl	1.76
Future \| Buy (Long) Contracts \| RBOB Gas Futures [Member] \| Not Designated As Hedging Instrument
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount \| bbl	4
Weighted average contract price per gal \| $ / bbl	1.59
Future \| Buy (Long) Contracts \| Fuel Oil Futures \| Not Designated As Hedging Instrument
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount \| bbl	70
Weighted average contract price per gal \| $ / bbl	48.51
Options \| Sell (Short) Contracts \| Crude Oil \| Not Designated As Hedging Instrument
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount \| bbl	50
Underlying, Derivative \| $ / bbl	0.63
Options \| Buy (Long) Contracts \| Crude Oil \| Not Designated As Hedging Instrument
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount \| bbl	20
Underlying, Derivative \| $ / bbl	0.19

- Definition

Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

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+ References

No definition available.

+ Details

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- Definition

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+ References

No definition available.

+ Details

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