Financial Instruments - Notional amounts (Details) - Not Designated as Hedging Instrument [Member] - Commodity Contract [Member] - bbl bbl in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Short [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	2,282	5,890	6,594	16,310
Long [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	2,821	5,743	6,952	16,253

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.

No definition available.

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