Derivative Contracts (Narrative) (Details)	12 Months Ended
Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Forecasted production from proved reserves (in hundredths)	100.00%
Expected Annual Production Covered By Derivatives, Low	50.00%
Expected Annual Production Covered By Derivatives, High	75.00%

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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Balance Type:	na
Period Type:	duration